United States Office of CERI-9M9 Environmental Protect! Research and Development May 1991 Agency Cincinnati Ohio 45268 x>EPA Contaminated Sediments Seminar Speaker Slide Copies ------- CERI-91-19 May 1991 CONTAMINATED SEDIMENTS SEMINAR Speaker Slide Copies Summer 1991 Printed on Recycled Paper ------- Notice The U.S. Environmental Protection Agency (EPA) strives to provide accurate, complete and useful information. However, neither EPA nor any person contributing to the preparation of this document makes any warranty, expressed or implied, with respect to the usefulness or effectiveness of any information, method, or process disclosed in this material. Nor does EPA assume any liability for the use of, or for damages arising from the use of, any information, methods, or process disclosed in this document. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. ------- Table of Contents Page Overview of Contaminant Problem and Remediation Approach for Uncontrolled Hazardous Waste Sites ....1-1 Physical/Chemical Characteristics of Sediments 2-1 Overview of Test Methods and Criteria for Evaluating Contaminated Sediments.... 3-1 Sampling Methods for Determining Extent of Contamination 4-1 Modeling of Contaminated Sediment Movement 5-1 Removal and Transport Processes 6-1 Dewatering and Other Pre-treatment Processes 7-1 Technology Screening and Integration Processes '. 8-1 Extraction Technologies 9-1 Thermal Technologies (Incineration, LT Desorption, Recovery Systems) 10-1 Bioremediation 11-1 Solidification/Stabilization 12-1 Residual Disposal Methods (Confined Disposal Facilities, Capping, and Landfills) 13-1 in ------- Overview of Contaminant Problem and Remediation Approach for Uncontrolled Hazardous Waste Sites Dr. Carol Bass U.S. Environmental Protection Agency Washington, D.C. Contaminated sediments may pose risks to both human and environmental health. Such sediments may be found in large sites, such as the harbors of industrialized ports. However, they are also frequently found in smaller sites, such as streams, lakes, bayous, and rivers. The Office of Emergency and Remedial Response (OERR) analyzed 486 Records of Decision (RODs) using the ROD Information Directory to obtain a list of Superfund sites identifying contaminated sediments as a human or ecosystem health concern. This list was subsequently evaluated for specific information regarding sediment contamination, response, action, methods, and performance goals. Twenty percent of these RODs, from 69 sites, addressed potential sediment contamination. Of these 69 sites, remediation was selected for 49; no remediation was selected for 20 (i.e., no excavation, treatment, or disposal). Of the 49 sites where remediation was selected, 30 chose excavation with treatment as the remedy. The remaining 19 sites utilized excavation followed by disposal (containment). Additional evaluations focused on the prevalence of contaminants of concern at all 69 sites. Of the 67 sites where specific sediment contaminants of concern were provided, 45 (67%) listed metals as contaminants of concern. The second most prevalent contaminant group was volatile organic compounds (VOCs). Other organic compounds frequently identified were polynuclear aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Cleanup goals varied between sites due to site specific applications of ARARs and risk assessment. 1-1 ------- EXTENT OF CONTAMINATED SEDIMENT PROBLEM 24% of National Priorities List Sites were found to have potentially contaminated sediments 20% of the Record of Decisions in the ROD Information Director addressed potential sediment contamination RODs: 69 SITES WITH CONTAMINATED SEDIMENTS Remediation Selected for 49 Sites No Remediation Selected for 20 Sites 1-2 ------- RODs: 49 REMEDIATED SITES 30 Chose Excavation with Treatment 13 incineration 10 solidification 2 biodegradation 1 dechlorination 1 in situ vitrification 3 to be determined RODs: 49 REMEDIATED SITES 19 Chose Excavation Followed by Disposal 10 off-site disposal 7 on-site disposal 2 on-site storage REASONS FOR NO REMEDIATION DECISIONS (20 ROD Sites) Contaminated sediments had been isolated (9 sites) Sediment monitoring (3 sites) Sediment treatment deferred (2 sites) No correlation between off-site and on-site contaminants (2 sites) Surface water diverted (2 sites) Fund balancing waiver invoked (1 site) Remediation a greater risk (1 site) 1-3 ------- METAL CONTAMINANTS OF CONCERN (67 ROD Sites) lead (26 sites/39%) chromium (18 sites/27%) cadmium (15 sites/22%) arsenic (13 sites/19%) zinc (13 sites/19%) all metals (45 sites/67%) ORGANIC CONTAMINANTS OF CONCERN (67 ROD Sites) VOCs (31 sites/46%) PAHs (24 sites/36%) PCBs (18 sites/27%) IDENTIFIED RISK FACTORS (69 ROD Sites) Threat to Human Health Extent of Sediment Contamination Toxicity of Contaminants Mobility of Contaminants Increased Risk Posed by Disruption of Contaminated Sediments Threat to Wildlife and Aquatic Life 1-4 ------- Physical/Chemical Characteristics of Sediments Dr. Robert P. Gambrell and Dr. William H. Patrick, Jr. Laboratory for Wetland Soils and Sediments Louisiana State University Baton Rouge, Louisiana Sediment is the material that settles to the bottom of any body of water. Its primary components are interstitial water and soil particles. Interstitial watercan comprise up to 90 percent of the total volume of unconsolidated, top sediment horizons and close to 50 percent of deeper, more compacted sediments. Soil particles found in sediments are derived from surface erosion of soils in the watershed, bank erosion, and redistribution of the bed load in waterways. Sediments vary widely in particle size distribution and are generally finer in texture than their source soils. Segregation of particle size occurs within the water body as a result of currents such that the smaller particles accumulate in quiescent zones and coarser particles are found where the current is greater. Organic matter, another important component of sediment, may range from near zero to greater than 10 percent of the sed iment solid phase. Minor (but not necessarily unimportant) components of sediments include shells and other animal parts, plant detritus, sewage, and industrial wastes such as metals, other inorganic chemicals, synthetic organic compounds, and oil and grease. Sediments are a very important part of aquatic ecosystems and in and of themselves should not be considered a problem. Sediments can become a problem when contaminated. Sediments are considered contaminated when anthropogenic sources of pollution exist in high enough concentrations and are sufficiently available to affect human and/or ecosystem health. Contaminants enter the water body from point sources (such as municipal and industrial effluents), non-point sources (such as agricultural and urban runoff), and other sources (such as spills, leaks, and dumping of wastes). Common contaminants of concern include halogenated hydrocarbons (PCBs, dioxins, many pesticides, etc.), polycyclic aromatic hydrocarbons (PAHs such as naphthalene, pyrenes, etc.), and other organics (such as benzene), as well as metals (including iron, manganese, lead, cadmium, and mercury). The physical and chemical characteristics of sediments exert a great deal of influence upon the bioavailability of sediment contaminants. These characteristics vary greatly from site to site. As a result, site characteristics should impact remediation decisions. The primary physical characteristic is texture, or the distribution of sand, silt, and clay sized particles. Generally, sandy sediments have little attraction for either toxic metals or synthetic organics (pesticides and industrial organics). Fine textured sediments such as silt and clay have a much greateraff inity for all classes of contaminants. Another very important physical property is the organic matter content, including humic material. Humic material is important in two respects: the humic material greatly increases the affinity of sediments for metals and nonpolar organic contaminants and it serves as an energy source for sediment microbial populations. Measurement of sediment in situ water content is also usually important to remediation decisions. The chemical properties of sediments also greatly affect the mobility and biological availability of contaminants. Important chemical analyses include pH, oxidation-reduction, salinity conditions, and sulf ide content as well as the amount and type of cations and anions, and the amount of potentially reactive iron and manganese. Contaminants may be mobilized or immobilized as the physical and chemical environment of the sediment changes during remediation operations. For example, metal carbonates may release their metals if the pH is reduced during removal and treatment. Understanding the influence of the sediment chemical environment, and controlling changes in this environment, are important to the selection of disposal alternatives for contaminated sediments. 2-1 ------- SEDIMENT: Major Components: Other Important Components: Animals and Detritus: Contaminants, if Present: Material that settles to the bottom of a body of water. eroded soil and interstitial water organic matter, iron oxides, sulfides, carbonates benthic organisms, shell, plant and animal detritus sewage, agricultural chemicals, oil and grease.and industrial chemicals such as metals, other inorganic chemicals, and synthetic organic compounds SEDIMENTS solids interstitial water PROPERTIES OF SEDIMENTS Physical: moisture content particle size distribution type of clay minerals organic matter content Chemical: pH redox potential salinity carbonate content amount and forms of sulfur reactive iron and hydrous oxides kinds and amounts of contaminants 2-2 ------- PARTICLE SIZE AND AFFINITY FOR CONTAMINANTS I C33 CD CZ3 § o gravel sand silt clay >50 microns [contaminants] 50-2 microns <2 microns [contaminants] [contaminants] PHYSICAL PROPERTIES Type of Clay Minerals \ kaolinite = 3-15cmol(+)kg-1 smectite = 80-120cmol(+)kg-1 PHYSICAL PROPERTIES Organic Matter Content Amount low high Paniculate Coatings 2-3 ------- Typical Range of pH and Redox Potential in Soils, Sediments, and Dredged Materials Sediments (pH 6.5 - 8.5) Upland Applied Dredged Sediments (pH 3.5 - 8.5) Upland Soils (pH 5.0 - 8.5) Marsh Soils, Spoil Banks (pH 3.5 - 8.0) I I -200 -100 strongly reducing i i i i i i i 0 100 200 300 400 500 600 REDOX POTENTIAL, mv well oxidized CONTAMINANTS IN SEDIMENTS Interstitial water for benthic organisms sediment solids metal contaminants organic contaminants CONTAMINANTS IN SEDIMENTS Interstitial water benthic organisms sediment solids Soluble concentrations of contaminants and biological availability are affected by physical and chemical properties of the sediment solid phase. 2-4 ------- GENERAL CHEMICAL FORMS OF TRACE AND TOXIC METALS IN SEDIMENTS Readily Available: dissolved exchangeable Potentially Available: - exchangeable precipitated, i.e., Me(OH)2 complexed with organic matter co-precipitated with hydrous oxides precipitated as sulfides Unavailable: fixed within the crystalline lattice structure of clay minerals DISSOLVED METALS free cation metal cation complexed with soluble ligands EXCHANGEABLE METALS © clay mineral 2-5 ------- SEDIMENT pH EFFECT ON METAL PRECIPITATION AND ADSORPTION low pH (acid) 4 near neutral or alkaline pH Me(OH)i Me2* precipitation and adsoprtion INFLUENCE OF CARBONATE CONTENT ON pH AND METAL FORMS UPON SEDIMENT OXIDATION Oxidized Dredged Material low carbonate may contribute to low pH upon oxidation high carbonate pH near neutral or higher MeCCXi Me2* h Me(OH),l METAL COMPLEXED BY HUMIC ACID 2-6 ------- LONG-TERM RESPONSE OF HUMIC ACID TO AN INCREASE IN REDOX POTENTIAL Reduced Environment Oxidized Environment + CO2 + Me2* HYDROUS IRON OXIDES Sediment particle with a coating of amorphous iron oxhydydroxides containing co-precipitated trace and toxic metals HYDROUS IRON OXIDES Oxidized Environment Reduced Environment Fe2+ + H20 Reaction: Fe203 + 6H* + 2e- 2Fe2* + 3H2O 2-7 ------- HYDROUS IRON OXIDE RESPONSE TO CHANGES IN pH AND REDOX POTENTIAL Reduced sediment, near neutral pH Oxidized sediment, near neutral pH Oxidized sediment, acid pH a Fe2* AMORPHOUS METAL SULFIDE PRECIPITATES SULFIDE PRECIPITATION Reduced Sediment Oxidized Interstitial Water MeSi insoluble metal sulfide precipitate Me2* + SO4- metals released from sulfide 2-8 ------- Clay particle or primary mineral containing trace/toxic metals in crystalline structure 2-9 ------- Overview of Test Methods and Criteria for Evaluating Contaminated Sediments Mr. Mike Kravttz, Mr. Chris Zarba, Mr. Tom Wall U.S. EPA Office of Water: Office of Science and Technology Washington, D.C. Addressing the toxicity of sediments and any potential threat they pose to human health and the environment is an important step in the remediation process. Several kinds of tools are available to use in making decisions concerning sediment quality assessment and desired levels of remediation. Primary tools include environmental regulations and sediment assessment methods. Brief descriptions of these tools, the development of nationally applicable sediment quality criteria, and a synopsis of EPA's agency-wide Sediment Management Strategy form the basis of this presentation. Under CERCLA, Superfund remedial action must meet any federal standards, requirements, criteria, or limitations that are determined to be legally applicable or relevant and appropriate requirements (ARARs). Environmental regulations can be a source of ARARs and should be understood as part of the assessment and remediation process. Major laws or agreements that relate to contaminated sediments will be briefly discussed; further information is available in Chapter II of the seminar handbook, "Remediation of Contaminated Sediments" (EPA 625/6-91/028) and "Contaminated Sediments: Relevant Statutes and EPA Program Activities" (EPA506/6-90/003, USEPA. 1990). To identify levels at which specific contaminants in sediment cause harmful effects, the EPA is developing nationally applicable sediment quality criteria using the equilibrium partitioning (EqP) method. The EqP approach uses water quality criteria and partitioning coefficients (between sediment sorbents and pore water) of specific contaminants to derive sediment quality criteria. The sediment quality criterion for a given contaminant is determined by calculating the sediment concentration of the contaminant that would correspond to an interstitial pore water concentration equivalent to the EPA water quality criterion for the contaminant. EqP-derived sediment quality criteria will soon be available for a number of non-ionic organic chemicals, and research is continuing on development of criteria for metals. EPA is also investigating other methods used to assess the quality of potentially contaminated sediments. A draft "Sediment Classification Methods Compendium" provides a description of each method, associated advantages and limitations, and existing applications. The sediment assessment methods described can be classified into two basic types: numeric ordescriptive. In particular, EPAis developing more sensitive toxicity tests to identify sediment problems caused by complex mixtures of contaminants. Though toxicity testing does not directly identify the problem contaminants, the use of techniques such as toxicity identification evaluation (TIE) allows one to identify contaminants most likely responsible for the observed toxicity. In January 1990, EPA's Sediment Steering Committee decided to prepare an agency-wide Sediment Management Strategy and formed four workgroups to draft options for the strategy. The workgroups are Assessment and Identification of Risk; Prevention; Remediation; and Management of Dredged Material. The staff on these workgroups prepared fourteen issue papers addressing such topics as the preparation of a national inventory of contaminated sites and of facilities that contaminate sediments; need for a consistent, tiered testing approach to assess sediment quality; and enforcement-based remediation. In May. afterconsidering input from EPA managers, other Federal and state agencies, the Steering Committee met to select preliminary options for the Strategy. This summer, a draft Strategy will be presented to industry and environmental groups for review. 3-1 ------- COORDINATING THE AGENCY'S CONTAMINATED SEDIMENTS ACTIVITIES Contaminated Sediments Steering Committee - Policy Coordination Contaminated Sediments Technical Committee - Coordinating Research, Technical, and Field Activities EPA SEDIMENT OVERSIGHT TECHNICAL COMMITTEE Sediment Classification Methods Compendium Contaminated Sediments: Relevant Statutes and EPA Program Activities Contaminated Sediments News Guidance on Selecting Techniques for Remediating Contaminated Sediments SOME MAJOR LAWS OR AGREEMENTS THAT RELATE TO CONTAMINATED SEDIMENTS Clean Water Act (CWA) Resource Conservation and Recovery Act (RCRA) Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Marine Protection, Research, and Sanctuaries Act (MPRSA) Toxic Substances Control Act (TSCA) Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Clean Air Act (CAA) National Environmental Policy Act (NEPA) Rivers and Harbors Act (RHA) U.S.-Canada Great Lakes Water Quality Agreement (GLWQA) 3-2 ------- CONTAMINATED SEDIMENTS: RELEVANT STATUTES AND EPA PROGRAM ACTIVITIES (U.S. EPA, 1990) Provides information on Program Office Activities relating to contaminated sediment issues, and the specific statutes under which these actitivites fall. OVERVIEW OF CRITERIA DEVELOPMENT EFFORT WATER QUALITY CRITERIA Protective of - Aquatic life (95%) - Human health Established Defensible 3-3 ------- WORKSHOP SEDIMENT CRITERIA DEVELOPMENT Legal Authority Review Approaches National Assessment November, 1984 UNCERTAINTY ANALYSIS Sediment Criteria Increasing Concentration I \\ Uncertainty BIOAVAILABILITY 3-4 ------- EQUILIBRIUM PARTITIONING APPROACH A sediment quality value for a given contaminant is determined by calculating the sediment concentration of the contaminant that would correspond to an interstitial water concentration equivalent to the EPA water quality criterion for the contaminant. EQUILIBRIUM PARTITIONING \ Non-Ionic Organics Metals Ionic Organics i Science Advisory Board Review POTENTIAL REGULATORY USES FOR SEDIMENT CRITERIA Superfund Dredging Ocean Dumping Monitoring Permitting Other 3-5 ------- SEDIMENT CLASSIFICATION METHODS COMPENDIUM Describes the Various Methods Used to Evaluate Sediment Contamination, Including Their Advantages, Limitations, and Existing Applications. (June 1989 draft is under revision.) SEDIMENT CLASSIFICATION METHODS COMPENDIUM [Sample Contents] Chapter 1. Introduction 1.0 Background 2.0 Objective 3.0 Overview Chapter 2. Bulk Sediment Toxicity Test Approach 1.0 Specific Applications 2.0 Description 3.0 Usefulness 4.0 Status SEDIMENT QUALITY ASSESSMENT METHODS Numeric Methods Method Type(s) of Data Spiked-sediment Toxicity Interstitial Water Toxicity Equilibrium Partitioning Tissue Residue Approach Sediment Quality Triad Apparent Effects Threshold Chemistry, Toxicity Chemistry, Toxicity Chemistry Chemistry, Toxicity Chemistry, Toxicity, In Situ Studies Chemistry, Toxicity, In Situ Studies 3-6 ------- SEDIMENT QUALITY ASSESSMENT METHODS Descriptive Methods Method Type(s) of Data Bulk Sediment Toxicity Freshwater Benthic Community Structures Marine Benthic Community Structures Sediment Quality Triad Toxicity In Situ Studies In Situ Studies Chemistry, Toxicity, In Situ Studies BULK SEDIMENT TOXICITY TEST APPROACH Test organisms are exposed in the laboratory to field-collected sediments. Mortality orsublethal effects in different sediments (sites) are compared quantitatively to one another or to effects observed in reference sediments. INTERSTITIAL WATER TOXICITY APPROACH (Toxicity Identification Evaluation) Toxicity of interstitial water is quantified and identifi- cation evaluation procedures are applied to identify and quantify chemical components responsible for sediment toxicity. 3-7 ------- BENTHIC COMMUNITY STRUCTURE (Freshwater, Marine) Environmental degradation is measured by evaluating alterations in benthic community structure. TISSUE RESIDUE APPROACH Sediment chemical concentrations that will result in acceptable residues in exposed biotic tissues are determined. 2-step process: 1. Link toxic efffects to residues (e.g., through dose-response relationships) 2. Link chemical residues in specific organisms to sediment chemical concentrations. SEDIMENT QUALITY TRIAD Examines the correspondence among three measures of sediment contamination: Concentrations of chemical contaminants in sediment Toxicity In situ studies (usually infauna data) 3-8 ------- APPARENT EFFECTS THRESHOLD APPROACH One possible way to derive a single index from trie triad components. An AET is the sediment concentration of a contaminant above which statistically significant biological effects (e.g., amphipod mortality in bioassays, depressions in abundance of benthic infauna) would always be expected. GUIDANCE ON SELECTING TECHNIQUES FOR THE REMEDIATION OF CONTAMINATED SEDIMENTS Will Provide Guidance on Selecting Procedures and Technology for the Remediation of Contaminated Sediments in Site-Specific Situations. (In draft form; final expected by end of FY91) EPA SEDIMENT MANAGEMENT STRATEGY Will establish national priorities for assessing sedi- ment problems, source controls, remediation efforts and dredged material disposal options. Being developed from the input of four workgroups: 1. Assessment and Identification of Risk 2. Prevention 3. Remediation 4. Management of Dredged Material 3-9 ------- EXTENT AND SEVERITY OF .SEDIMENT CONTAMINATION Should We Do a National Inventory? - S/feswith Contamination - Sources of Contamination Who Will Take the Lead? How Will We Do an Inventory? - New vs. Existing Data - General Extent of Problem vs. List of Specific Sites/Sources - Ranking System for Follow-up Actions Resource Needs STRATEGY ISSUE: How Do We Define the Extent and Severity of the Risks of Sediment Contamination? Should We Use Consistent Tiered Testing Across All EPA Programs? - Agree on a hierarchy of biological effects-based testing and physical/chemical analysis. - Testing continues until a clear basis for decision is reached on whether sediment poses risks to aquatic life or humans consuming fin fish and shellfish. - Good progress has been made in developing a variety of tests for tiered system. - Difficulty lies in how each program will decide "How Clean is Clean" based on test results. PREVENTING SEDIMENT CONTAMINATION Existing Programs - Sediment criteria - Effluent guidelines - Point source controls - Nonpoint source controls - Reviewing pesticides - Reviewing toxic chemicals Issue: How Do We Implement a Prevention Strategy? - Consistent tiered testing - Guidance, Procedure changes - Resource needs 3-10 ------- REMEDIATING CONTAMINATED SEDIMENTS Existing Programs OSWER Supertund and RCRA Corrective Action Programs - a few cases CWA Section 115 - no funding received Enforcement-Based Remediation - several recent cases CWA CERCLA RCRA TSCA REMEDIATING CONTAMINATED SEDIMENTS (cont.) Issues How do We Determine the Need for Remediation? How do We Select Cleanup Goals How Do We Implement a Remediation Strategy? - Statuatory Changes Guidance and Procedure Changes - Resource Needs MANAGING DREDGED MATERTIALS Existing Programs Ocean Dumping Programs - national tiered testing system under revision CWA Section 404 Program - first draft of a national tiered testing program issues - Evaluting the Need for Restrictions on Disposal - Improving the Balance of Environmental and Economic Factors - Resource Needs 3-11 ------- Sampling Methods for Determining Extent of Contamination Mr. Jan A. Miller U.S. Army Corps of Engineers Chicago, Illinois Characterization of contaminated sediments begins with the identification of contaminants present and a description of the vertical and horizontal distributions of the contaminants within the sediments. Characterization of the sediments is also-Important, as sediment characteristics will have profound effects on contaminant availability and should impact remediation decisions. Sediment characterization should include physical and chemical characteristics but also distributions of these within the site of concern. In order to properly sample and characterize contaminated sediments, extensive planning must first be done. The sequence in the planning stage should include: 1. Identification of sampling purposes and objectives. 2. Compilation of available data on the site of concern. 3. Collection of preliminary field data. 4. Development of a detailed sampling plan. Developing a sampling plan appropriate for the site and sampling objectives increases the quality of the site characterization and minimizes characterization costs. Unfortunately, due to site variability, a systemized sampling plan applicable to all sites is not feasible. There are a number of sampling devices that are presently being used to collect sediment samples, including core samplers, grab samplers, and spoons, scoops, and trowels. There are many different types of core samplers that may be used for sediments. Some hand held units can be operated from small vessels. Some core samplers require the use of a tripod or truck mounted drill rig operated on a floating plant (barge). Core sampling devices include the split-spoon, the piston-tube or Chicago tube, the vibracore, and hand augers. Grab samplers, such as the Ponar and Eckman dredge samplers, are small, lightweight, and can be operated by hand from a small boat. They only collect surface sediments (top 3-6 inches). They have problems with any consolidated (hard packed) deposits. For larger volumes of sample, sometimes needed for treatability tests, a small, commercial clamshell dredge (1-3 cubic yard bucket) can be used. Spoons, scoops, and trowels are only useful in shallow water. They are less costly than other samplers, easy to use, and may be useful if numerous samples are intended; their low cost allows disposal between sample sites. Core samplers are generally preferred over other samplers because (1) core samplers can sample to greaterdepth, (2) core samplers maintain the complex integrity of the sediment, and (3) core samplers do not disturbthe substrate as much as other sampling procedures. Grab samplers, on the other hand, are less expensive, easier to handle, and often require less manpower than core samplers. Unfortunately, grab samplers cause considerable disruption of the sediment. Dredge samplers promote loss of the fine-grained fraction of the sediment as well as water soluble compounds and volatile organic compounds which may be present in the sediment. Spoons, scoops, and trowels are somewhat undesirable because the reproducibility of sampling area, depth, and volume from one sampling site to another is poor. They also tend to disrupt the sediment during sampling. The type of chemical and physical analyses performed on sediment collected is specific to the purpose and objectives of the plan. There is no "standard" laundry list of analyses which is appropriate to all cases. 4-1 ------- DEVELOPMENT OF A SAMPLING PLAN 1. Identification of sampling purposes and objectives. 2. Compilation of available data on the site of concern. 3. Collection of preliminary field data. 4. Development of a detailed sampling plan. IDENTIFICATION OF SAMPLING PURPOSES AND OBJECTIVES 1. Determine distribution of specific contaminants. 2. Determine sediment contaminant mobility. 3. Determine existing impacts on aquatic/benthic fauna. 4. Determine disposal alternatives (regulatory). 5. Determine disposal alternatives (treatability). COMPILATION OF AVAILABLE DATA 1. Water depths/tidal fluctuations. 2. Obstructions (bridges, pipelines, etc.). 3. Access sites for mobilizing equipment. 4. Sediment depths (dredging or construction history). 5. Sources of contaminants (point and non-point) and other factors affecting contaminant distributions. 6. Hydraulic/other factors affecting sediment distribution. 7. Historic sediment quality data. 8. Survey benchmarks (for referencing sediment and water elevations). 4-2 ------- COLLECTION OF PRELIMINARY FIELD DATA Helps minimize the costs of sampling and of laboratory analyses. DEVELOPMENT OF A DETAILED SAMPLING PLAN 1. Locations of samples (lateral and vertical) 2. Types of samples (grab or core) 3. Number and volumes of samples required 4. Sampling procedures and equipment 5. Supporting vessels/equipment 6. Types of analytical tests required 7. Quality Assurance Program Plan (QAPP) for sampling and analysis 8. Cost estimate SEDIMENT SAMPLING DEVICES INCLUDE: 1. Core Samplers 2. Grab Samplers 3. Spoons, Scoops, and Trowels 4-3 ------- ADVANTAGES OF CORE SAMPLERS 1. Core samplers sample to greater depth. 2. Core samplers maintain sediment integrity. 3. Core samplers do not disturb the substrate as much as other sampling procedures. LIMITATIONS OF CORE SAMPLERS 1. Core samplers do not work well in sandy or rocky substrates. 2. Core samplers collect smaller amounts of sediment and may require additional sampling. 3. Most core samplers are expensive. 4. Most core samplers are difficult to handle and, consequently, have limited use under moderate wave conditions. CORE SAMPLERS INCLUDE: 1. Split-spoon 2. Piston-tube or Chicago Tube 3. Vibracore 4. Hand Augers 4-4 ------- ADVANTAGES OF GRAB SAMPLERS OVER CORE SAMPLERS 1. Less expensive 2. Easier to handle 3. Require less manpower LIMITATIONS OF GRAB SAMPLERS 1. Can cause considerable disruption of the sediment. 2. Can promote loss of the fine-grained fraction of the sediment as well as water soluble compounds and volatile organic compounds which may be present in the sediment. TYPICAL GRAB SAMPLERS: 1. Ponar 2. Eckman 4-5 ------- ADVANTAGES OF SPOONS, SCOOPS, AND TROWELS 1. Cheap 2. Easy to use 3. Applicable for numerous sample collections LIMITATIONS OF SPOONS, SCOOPS, AND TROWELS 1. Reproducibility of sampling area, depth, and volume is poor. 2. Tend to disrupt the sediment during sampling. OTHER SAMPLING CONSIDERATIONS 1. Contaminants in the interstitial water 2. Container material for transportation of samples 3. Preservation of samples 4. Storage time of samples 5. Volume requirements for laboratory analyses 4-6 ------- COMMON PHYSICAL ANALYSES: 1. Particle size and distribution 2. Organic carbon or volatile matter content 3. Total solids/specific gravity COMMON CHEMICAL ANALYSES: 1. pH 2. Oxidation-reduction 3. Salinity conditions 4. Sulfide content 5. Amount and type of cations and anions 6. Amount of potentially reactive iron and manganese 4-7 ------- Modeling of Contaminated Sediment Movement Dr. Stephen C. McCutcheon U.S. Environmental Protection Agency Athens, Georgia Models applicable to contaminated sediments include sediment transport and contaminant transport and fate models. These models have several applications including: (1) they can be used as a screening tool in predicting the environmental and health impacts from contaminant exposure during various remediation actions and (2) they can be used diagnostically to investigate sources of contamination. Current models are limited in their predictive ability to function as a screening tool or crude design model, but are developed to such a degree that they are being applied in this respect to the Buffalo River, New York. Diagnostic modeling is being done at the Sheboygan River, Wisconsin. Sediment transport models are linked to hydrodynamic models and predict sediment movement due to circulation. Different models have been developed for a variety of sediment environments including lakes, harbors, estuaries, coastal areas, and rivers. The models may be one-, two-, orthree-dimensional, depending on the nature of the water body. The one-dimensional models, HYDRO1D-DYNHYD, HYDRO1D-RIVMOD, and HSPF, are used for rivers, streams, and watersheds. The two-dimensional model, HYDRO2D-V, is generally the first choice of the Environ- mental Research Laboratory (ERL) and has application for estuaries, shallow lakes and bays, and streams. The HYDRO2D-V is being used to model arsenic contamination in New Jersey and is planned for use at Montana mining district streams and in modeling the south bay of San Francisco Bay. The three-dimensional model, HYDRO3D- V, has application for stratified bodies of water, such as lakes, and has been tested in PCB studies for Green Bay, Wisconsin. These models are in different stages of refinement, but all are available from the ERL in Athens, Georgia. Fate and transport models mimic the physical and chemical environment of sediments and predict how contaminants and sediments interact, particularly as conditions change. The HYDRO2D-V, also used as a sediment transport model, has been used to model adsorbed contaminants, but does not incorporate other contaminant processes. The WASP4 model is a general purpose, mass balance model incorporating a number of parameters and is considered the state-of-the-art fate and transport model by ERL and a number of EPA offices. The WASP4 has been adopted fortoxics management by the Great Lakes National Program Office. Studies using WASP4 focus on Green Bay, Lake Ontario, and Saginaw Bay. The WASP4 also simulates fish and food chain bioaccumulation and is being used to model these at the Buffalo River, New York; the Sheboygan River, Wisconsin; and Saginaw Bay, Michigan. 5-1 ------- EXPOSURE AND ECORISK TECHNICAL SUPPORT CENTER ATHENS, GEORGIA AREAS OF SUPPORT Geochemical Speciation Contaminant Transport in Soil-Groundwater Systems Sediment-Contaminant Transport in Surface Water Ecological Risk Assessment Simulation Modeling GEOCHEMICAL SPECIATION PROBLEMS Leaching, Mobility of Metals Potential Bioavailability of. Metals 5-2 ------- SEDIMENT-CONTAMINANT TRANSPORT IN SURFACE WATER PROBLEMS Existing Contaminant Migration, Risk Human, Ecological Risk following Remediation SEDIMENT-CONTAMINANT TRANSPORT IN SURFACE WATER EXAMPLES Clark Fork River/Milltown Reservoir Vineland Chemical Sheboygan Harbor MODEL: WASP4 DIMENSIONS: 0-Dimensional (multi-dimensional) DESCRIPTION: WASP4 is a dynamic compartment modeling system that can be used to analyze a variety of water quality problems in a diverse set of water bodies. 5-3 ------- MODEL: HSPF DIMENSIONS: 1-Dimensional DESCRIPTION: The Hydrologic Simulation Pro- gram (HSPF) is a comprehensive package for simu- lation of watershed hydrology and water quality for both conventional and toxic organic pollutants. MODEL: SED2D DIMENSIONS: 2-Dimensional DESCRIPTION: SED2D is a finite element model- ing system for simulating 2-dimensional (depth- averaged) surface water and cohesive sediment transport. MODEL: SED3D DIMENSIONS: 3-Dimensional DESCRIPTION: SED3D is a finite difference modeling system for calculating 3-dimensional unsteady currents and sediment transport in lakes and estuaries. 5-4 ------- ECOLOGICAL RISK ASSESSMENT PROBLEM Assess Ecological Risk from Present Contaminants ECOLOGICAL RISK ASSESSMENT EXAMPLES New Jersey Zinc/Eagle River Clear Creek/Central City DuPont Newport Nascolite Site U.S. EPA CENTER FOR EXPOSURE ASSESSMENT MODELING OFFICE OF RESEARCH AND DEVELOPMENT ATHENS, GEORGIA 5-5 ------- MODEL SUPPORT Surface Water - Quality Surface Water - Dilution, Hydrodynamics Runoff and Erosion Soil and Groundwater SURFACE WATER - QUALITY Conventional Water Quality Chemical Transport and Fate Sediment Transport Metals Speciation Fish Bioaccumulation SURFACE WATER - DILUTION, HYDRODYNAMICS » Mixing Zone Analysis Pollution Dilution Hydrodynamics 5-6 ------- RUNOFF AND EROSION Urban Rural SOIL AND GROUNDWATER Chemical Transport Metals Speciation Subsurface Hydrology SURFACE WATER QUALITY MODELS QUAL2E stream water quality WASP4 general water quality, chemical fate HSPF upland stream water quality, chemical fate EXAMS general chemical fate FGETS fish bioaccumulation SED2D-V 2-dimensional, vertically integrated cohesive sediment transport MINTEQ metals speciation 5-7 ------- RUNOFF, SOIL, AND GROUNDWATER MODELS PRZM pesticide root zone transport MULTIMED multimedia hazardous waste screening RUSTIC soil and groundwater pesticide transport HSPF watershed runoff, erosion SWMM urban stormwater runoff MINTEQ metal speciation WASP4 GENERAL WATER QUALITY ANALYSIS MODEL Waste Load Allocation of Conventional and Toxic Pollutants Dynamic Water Quality Ponds, Rivers, Lakes, Estuaries Simple 1-D to Multidimensional Networks Linkage to Hydrodynamic Models Linkage to Loading Models Surface Water - Benthic Sediment Interaction Dissolve Oxygen Balance Simple Sediment Balance Nutrient Cycling and Phytoplankton Growth Chemical Transport and Fate Linkage to Bioaccumutation Models EXAMS2 ORGANIC CHEMICAL EXPOSURE ANALYSIS MODEL Screening and Evaluation of Organic Chemicals in Aquatic Systems Steady-state and Quasidynamic Pollutant Fate Ponds, Rivers, Lakes Simple 1-D to Multidimensional Networks Linkage to Loading Models Surface Water - Benthic Sediment Interaction Chemical Transport and Fate Linkage to Bioaccumulation Models 5-8 ------- MINTEQA2 GEOCHEMICAL EQUILIBRIUM - METALS SPECIATION MODEL Exposure Assessment of Metals Equilibrium Speciation of Metals, Ions, Ligands Groundwater and Surface Water Organic and Inorganic Complexation, Sorption, and Precipitation/Dissolution Thermodynamic Data Base over 1400 Species 13 Trace Metals/Metalloids of Major Concern: Ag, As, Ba, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Se, Ti, Zn FGETS ORGANIC CHEMICAL BIOACCUMULATION MODEL Risk Assessment for Bioaccumulation of Organic Chemicals in Fish Pharmokinetics Based on Gill and Gut Exchange of Nonmetabolized Organic Chemicals Physiological and Morphological Data Base Dynamic Exposure Simple Food Chains Linkage from Chemical Fate Models Internal Partitioning to Blood, Fat, Structure Estimates Death by Narcosis Predicts Relative Significance of Exposure Routes HSPF HYDROLOGIC SIMULATION OF UPLAND WATERSHEDS Pesticide Exposure Assessment, Nonpoint Source Load Allocation Dynamic Runoff, Water Quality, Pollutant Fate Uplands Watershed Pervious and Impervious Land Segments Branching Stream Network Sediment Erosion and Transport Nutrient Runoff, Erosion, and Transport Pesticide Runoff, Erosion, and Transport Surface Water - Benthic Sediment Interaction Dissolved Oxygen Balance Phytoplankton 5-9 ------- SWMM URBAN STORM WATER MANAGEMENT MODEL Hydraulic and Runoff Quality Analysis of Urban Drainage Networks Single Event or Continuous Simulation Catchment Schematization Course or Fine Pollutant Buildup on Catchments Rainfall, Snowmelt, Runoff Flow Routing through Drainage Network Dynamic Flow through Sewer Pipes Storage and Treatment PRZM PESTICIDE ROOT ZONE MODEL Exposure Assessment, Leaching Potential of Pesticides Runoff, Erosion, and Vertical Leaching Hydrologic Component - SCS Curve Number Technique Water Movement by Generalized Soil Terms Chemical Transport, Partitioning, Decay Linkage to Surface Water Models ENVIRONMENTAL MODELING SOFTWARE AT THE USEPA CENTER FOR EXPOSURE ASSESSMENT MODELING Athens, GA (404-546-3549) water quality, exposure assessment, surface water, soil, groundwater, multimedia 5-10 ------- ENVIRONMENTAL MODELING SOFTWARE AT THE USEPA ATMOSPHERIC SCIENCES RESEARCH LABORATORY RTP.NC (919-541-4564) air dispersion, human exposure (UNAMAP Series) ENVIRONMENTAL MODELING SOFTWARE AT THE USEPA OFFICE OF TOXIC SUBSTANCE Washington, D.C. (202-382-3894) Graphical Exposure Modeling Systems - GEMS, PCGEMS exposure models, surface water, soil, groundwater, air, multimedia estimation techniques environmental data ENVIRONMENTAL MODELING SOFTWARE AT THE USEPA OFFICE OF HEALTH AND ENVIRONMENTAL ASSESSMENT Washington, D.C. (202-475-8924) RISK * ASSISTANT human risk assessment various exposure pathways 5-11 ------- Removal and Transport Processes Mr. Steve Garbaciak U.S. Army Corps of Engineers Chicago, Illinois The process of selecting removal and transport technologies should be driven by treatment and/or disposal decisions. This is because treatment/disposal options typically have the higher costs and are more controversial from a social, political, or regulatory perspective. A primary concern during the removal and transport of contaminated sediments is the danger of introducing con- taminants into previously uncontaminated areas. Contamination during these steps occurs primarily from the resuspension of sediments during removal and from spills and leaks during transport. To increase efficiency and reduce sediment resuspension, dredges, operational controls, and barriers should be used together. Of these, dredges actually remove the sediments; operational controls and barriers minimize the resuspension and spread of contaminated sediments during removal. Dredges available for the removal of contaminated sediments include mechanical and hydraulic. Mechanical dredges remove sediments by the direct application of mechanical force to dislodge sediment material. The most commonly used mechanical dredge is the clamshell dredge which has widespread application for the removal of contaminated sediments, although the use of a modified, watertight bucket may be required. Hydraulic dredges use centrifugal pumps to remove sediments in a liquid slurry form. They are widely available in the U.S. Often a cutterhead, or similar device, is fitted to the suction end of the dredge to assist in dislodging bottom materials. New dredge designs attempt to reduce the amount of resuspension caused by dredging and to decrease the water content of the pumped slurry. Operational controls include the cutter speed, the depth of cut, the swing speed and/or speed of advance, and the positioning of equipment. Operator experience is of primary importance in implementing operational controls. Barriers help reduce the environmental impact of sediment removal. Structural barriers include dikes, sheet pilings, caissons, and other weir enclosures. Non-structural barriers include oil booms, pneumatic barriers, sediment traps, silt curtains, and silt screens. Application of barrier options is site specific and functions to control contaminants only during removal. The primary emphasis during transport is towards spill and leak prevention. Transport options include pipelines, barges or scows, railroads, trucks, or hopper dredges. Selection of transport options will be affected by both dredge selection and pre-treatment and treatment decisions. 6-1 ------- REMOVAL AND TRANSPORT PROCESSES FOR CONTAMINATED SEDIMENTS CONTAMINATED SEDIMENT REMEDIATION COMPONENTS 1. Removal 2. Transport 3. Pre-treatment 4. Treatment 5. Disposal 6. Effluent/leachate treatment DREDGING METHODS 1. Mechanical 2. Hydraulic 6-2 ------- MECHANICAL DREDGES 1. Dipper 2. Bucket ladder 3. Dragline 4. Clamshell BUCKET DREDGE DIPPER DREDGE 6-3 ------- CLAMSHELL DREDGE PLAIN SUCTION HYDRAULIC DREDGES 1. Plain Suction 2. Cutterhead 3. Dustpan 4. Others 6-4 ------- CUTTERHEAD DREDGE CUTTERHEAD LAOOC/I HCAO CUTTER SHAFT LOOSE MATSHIAL \ O«£ DGf D SOTTO DUSTPAN DREDGE U JZ. _ r-ANCHOM LINES 6-5 ------- MUD CAT DREDGE - DISCHARGE UNE D ANCHOR 'LINE --L 1 AUGER ADVANTAGES OF MECHANICAL DREDGES 1. In-situ water content 2. Maneuverability 3. Debris removal DISADVANTAGES OF MECHANICAL DREDGES 1. Resuspension 2. Rehandling 3. Lower production rate 6-6 ------- ADVANTAGES OF HYDRAULIC DREDGES 1. Limited resuspension 2. No rehandling 3. High production rate DISADVANTAGES OF HYDRAULIC DREDGES 1. Large water volume 2. Pipeline 3. Debris DREDGING IMPACT CONTROLS 1. Closed bucket 2. Operations 3. Barriers 6-7 ------- WATERTIGHT BUCKET FOR CLAMSHELL DREDGE 0 COVER 0 COVER 0 RUBBER PACKING OR WELDED TONGUE AND GROOVE 0 ROD CUTTERHEAD DREDGE - PLAN VIEW This view illustrates operation complexity of a cutterhead and, thus, the importance of operator experience. TRANSPORT TECHNIQUES 1. Pipeline 2. Barge/scow 3. Others 6-8 ------- DREDGE TYPE SELECTION FACTORS 1. Volume 2. Location 3. Material 4. Pre-treatment VOLUME FACTORS 1. Economy of scale 2. Production rate LOCATION FACTORS 1. Obstacles 2. Areal layout 3. Distance to disposal 4. Time limits 6-9 ------- Dewatering and Other Pre-treatment Processes Pre-treatment technologies are defined as those methods that prepare dredged materials for additional treatment and/or disposal activities. Pre-treatment decisions are greatly influenced by dredging, treatment, and disposal decisions. Pre-treatment technology types include dewatering, particle classification processes, and slurry injections. They are primarily applicable to hydraulically dredged sediment. The objective of dewatering is to reduce the water content (increase the solid content) of sediments for one of the following reasons: dewatering improves dredged material handling characteristics; dewatering reduces treatment costs; dewatering reduces transportation costs; and dewatering is required prior to land disposal. Dewatering technologies can be subdivided into two general processes: air drying processes and mechanical processes. "Air drying" refers to those dewatering techniques by which the moisture is removed by natural evaporation and gravity or by induced drainage. Air drying is less complex, easier to operate, and requires less operational energy than mechanical dewatering. Air drying also can produce a dryer sediment than mechanical dewatering. The most widely applicable and economical air drying process available for sediments is an appropriately managed confined disposal facility (CDF). Mechanical dewatering involves processes in which water is forced out of the sediment through mechanically induced pressures. Mechanical dewatering processes include the following: filtration, including belt filter presses, chamber filtration, and vacuum rotary filtration; centrifuges, including solid bowl and basket; and gravity thickening. Particle classification technologies separate the slurry according to grain size or removes oversize material that is incompatible with subsequent processes. Classification by grain size is important in the management of sediments contaminated with toxic materials since the contaminants tend to adsorb primarily onto fine grain clay and organic matter. The small grain solids of a specific size or less can be treated while the relatively non-contaminated, coarser soils and sediments can be disposed of with minimal or no additional treatment. Particle classification technologies include: impoundment basins, hydraulic classifiers, hydrocyclones, grizzlies, and screens. Slurry injection is the injection of chemicals, nutrients, or microorganisms into the dredged slurry. Chemical injections condition the sediment for further treatment and/or accelerate the settling of suspended solids. Nutrient and/or microbe injections may enhance biodegradation of organics, either by providing a suitable environment for microbe growth or by supplying the microbes themselves. The amount of handling and rehandling required by various pre-treatment options will also influence pre-treatment decisions. Especially with severely contaminated sediments, all equipment that comes in contact with the sediments will require subsequent decontamination. Furthermore, rehandling also mechanically disrupts the sediments and increases the probability of introducing contaminants into the environment. Conversely, a series of pre-treatment steps requiring rehandling may bethe most efficient way of separatingthe contaminated sediments and preparing them for treatment. The water generated during dewatering generally contains suspended solids and may contain contaminants. Its quality may exceed effluent standards for receiving waters and may, therefore, require further treatment or a permit for discharge. 7-1 ------- PRE-TREATMENT TECHNOLOGIES ARE... those methods that prepare dredged materials for additional treatment and/or disposal activities. PRE-TREATMENT OBJECTIVES: 1. To enhance or accelerate settling of the dredged material solids. 2. To reduce the water content of the dredged material solids. 3. To separate coarser solids from fine-grained solids. 4. To reduce the overall cost of the remedial action. PRE-TREATMENT TECHNOLOGY TYPES 1. Dewatering 2. Particle classification 3. Slurry injection 7-2 ------- PRE-TREATMENT DEFINITIONS: 1. Percent Solid (Solid Content) 2. Percent Water (Water Content) 3. Percent Moisture (Moisture Content) DEWATERING ADVANTAGES 1. Improved handling characteristics 2. Reduced treatment costs 3. Reduced transportation costs 4. Required prior to land disposal DEWATERING TECHNOLOGIES 1. Air Drying Processes 2. Mechanical Processes 7-3 ------- MECHANICAL DEWATERING PROCESSES INCLUDE: 1. Belt - filter presses 2. Chamber filter presses 3. Vacuum rotary filter presses 4. Centrifuges 5. Gravity thickeners BELT FILTER PRESS Independent High Pressure Section CHAMBER FILTER PRESS 7-4 ------- VACUUM ROTARY FILTRATION BASKET CENTRIFUGE Feed! Basket Wall / Filler Paper (Used With Perforated Wall) Effluent SOLID BOWL CENTRIFUGE Drive Assembly Rotor Drive Assembly Solids Discharge 7-5 ------- PARTICLE CLASSIFICATION TECHNOLOGIES... separates the slurry according to grain size or removes oversized material. PARTICLE CLASSIFICATION IS IMPORTANT BECAUSE... contaminants tend to sorb to fine grain clay and organic material. PARTICLE CLASSIFICATION PROCESSES INCLUDE: 1. Impoundment basin 2. Hydraulic classifiers 3. Hydrocyclones 4. Grizzlies 5. Screens 7-6 ------- TYPICAL IMPOUNDMENT BASIN Plan use c*«mro m. ^^:: ::::: ««f A FO* iCD«(NiMriON ^v : ^ ""-^ ^ TYPICAL IMPOUNDMENT BASIN Cross Section D»fDC£0 U riKUI. r»ui. jroMCf TYPICAL CYCLONE 7-7 ------- SLURRY INJECTION TYPES 1. Chemical injections (coagulants and flocculants) 2. Nutrient injections 3. Microbe injections TYPICAL CONFIGURATION OF AN ANIONIC POLYMER IN SOLUTION © © © USE OF A PRE-TREATMENT TRAIN? 7-8 ------- Technology Screening and Integration Processes Dr. George Hyfantis International Waste Management Systems Knoxville, Tennessee Technology screening is the systematic appraisal of remediation approaches in orderto select the most appropriate alternative(s). The first step in this appraisal is to determine treatment goals. In determining treatment goals, questions of whetherto remediate a site and what degree of cleanup is necessary should be addressed. Once these questions are answered, methods to be used in achieving the desired remediation can be determined. Contaminants and contaminant concentrations vary widely between sites and within sites. Furthermore, there is usually a high degree of variability among site characteristics. Because of these sources of variability, selection of appropriate and feasible remediation techniques for contaminated sediments is a complex task. No simple management plan or screening procedure exists for selecting among available options. A screening logic is needed that can take into account specific site factors, the degree of protection required, costs, and availability and reliability of cleanup alternatives. The fundamental steps in searching for a feasible technology to remediate a contaminated sediment are to: (1) identify site and contaminant characteristics, (2) develop a list of treatment options, and (3) conduct a detailed evaluation of the possible treatments. ^ The "treatment train approach", an integration process, is a valuable concept for remediating contaminated sediments. Taking such an approach acknowledges the complexity of dealing with contaminated sediments and the fact that a multifaceted approach, combining several technologies into a sequence of steps, may permit more flexibility in addressing problems. In many cases, a treatment train may be essential to clean up sediments containing different types of contaminants. The term "side stream" refers primarily to the need to address contaminants generated by primary technologies. Forexample, while incineration may effectively destroythe organic contaminants in dredged material,the off-gases and/or ash may contain other types of contaminants. Thus, "side stream" treatment may be required to furthertreat contaminants collected. Necessary side stream technologies would be part of the overall evaluation for a remediation approach. 8-1 ------- TREATMENT TECHNOLOGIES SCREENING OF FEASIBLE TECHNOLOGIES PROCESS 1. Site and contaminant characteristics 2. Based on site evaluation list appropriate technologies 3. Evaluate each treatment option 8-2 ------- TREATMENT TRAIN APPROACH Sequenced technologies must be compatible The correct sequence must be chosen Consider effects/impacts of by-products ESTABLISH THE CLEAN UP GOALS OF THE SITE 8-3 ------- BIOLOGICAL TECHNOLOGIES CONSIDERED FOR NEW BEDFORD HARBOR SEDIMENTS For For Sediment Water PCB Metal Matrix Matrix Treatment Removal Advanced Biological Methods Yes No Yes No Aerobic Biological Methods No Yes No No Anaerobic Biological Methods Yes No No No Composting Yes No No No Land Spreading Yes No No No PHYSICAL TECHNOLOGIES CONSIDERED FOR NEW BEDFORD HARBOR SEDIMENTS Air Stripping Soil Aeration Carbon Adsorption Flocculatbn/Precipitatbn Evaporation Centrifugation Extraction Filtration Solidification Sediment Matrix No Yes No No Yes Yes Yes Yes Yes Water Matrix Yes No Yes Yes Yes No No No No For PCB Treatment No No Yes Yes No No Yes No Yes For Metal Removal No No No Yes No No No No Yes PHYSICAL TECHNOLOGIES CONSIDERED FOR NEW BEDFORD HARBOR SEDIMENTS (cont.) Granular Media Filtration In Shu Adsorption Ion Exchange Molten Glass Steam Stripping Supercritical Extraction Vitrification Particle Radiation Microwave Plasma Sediment Matrix No Yes No No No Yes Yes No No Water Matrix Yes No Yes No Yes No No No No For PCB Treatment No Yes No Yes No Yes Yes Yes Yes For Metal Removal Yes No Yes No No No Yes No No 8-4 ------- PHYSICAL TECHNOLOGIES CONSIDERED FOR NEW BEDFORD HARBOR SEDIMENTS (cont.) Crystallization Dialysis/Electrodialysis Distillation Resin Adsorption Reverse Osmosis Ultrafiltration Acid Leaching Catalysis Sediment Matrix No No No No No No Yes No Water Matrix Yes Yes Yes Yes Yes No No No For PCB Treatment No No No No No No No No For Metal Removal No No No Yes Yes No Yes No CHEMICAL TECHNOLOGIES CONSIDERED FOR NEW BEDFORD HARBOR SEDIMENTS Alkali Metal Dechlorination Alkaline Chlorination Catalytic Dehydrochlorination Electrolytic Oxidation Hydrolysis Sediment Matrix Yes No No No No Water Matrix No No No No Yes For PCB Treatment Yes No Yes No No For Metal Removal No No No No No CHEMICAL TECHNOLOGIES CONSIDERED FOR NEW BEDFORD HARBOR SEDIMENTS (cont.) Chemical Immobilization Neutralization Oxidation/Hydrogen Peroxide Ozonation Polymerization Ultraviolet Photolysis Sediment Matrix Yes Yes Yes No Yes No Water Matrix No No Yes No No No For PCB Treatment No No No No No Yes For Metal Removal Yes No No No No No 8-5 ------- THERMAL TECHNOLOGIES CONSIDERED FOR NEW BEDFORD HARBOR SEDIMENTS Electric Reactors Fluidized Bed Reactors Fuel Blending Industrial Boilers Infrared Incineration In Situ Thermal Destruction Liquid Injection Incineration Sediment Matrix Yes Yes No No Yes No No Water Matrix No No No No No No No For PCB Treatment Yes Yes Yes Yes Yes Yes Yes For Metal Removal No No No No No No No THERMAL TECHNOLOGIES CONSIDERED FOR NEW BEDFORD HARBOR SEDIMENTS (cont.) Molten Salt Multiple Hearth Incineration Plasma Arc Incineration Pyrolysis Processes Rotary Kiln Incineration Wet Air Oxidation Supercritical Water Oxidation Sediment Matrix No Yes No Yes Yes No Yes Water Matrix No No Yes No No Yes Yes For PCB Treatment Yes Yes Yes Yes Yes No Yes For Metal Removal No No No No No No No 8-6 ------- Extraction Technologies Mr. Dennis Timberlake U.S. Environmental Protection Agency Cincinnati, Ohio Extraction technologies remove organic or metallic contaminants from sediments but do not destroy or chemically alter contaminants. Effluent streams will be much more concentrated with contaminants than was the original sediment. Extraction technologies should be viewed as one part of a treatment train since organic contaminants still need to be destroyed after extraction. The contaminant-rich effluentfrom extraction technologies can be treated by any of a number of thermal, physical/chemical, and/or biological treatment technologies. By concentrating the contaminants in a smaller volume of sediment or residual, a significant cost savings may be realized. Traditionally, the term "extraction" has referred to chemical extraction but as used here it refers to a larger group of technologiesthat essentially achieve volume reduction by removing a contaminant from a waste stream and then concentrating it. For example, soil washing is usually thought of as being separate from chemical extraction, but using the present definition soil washing is considered an extraction technology. Soil washing is a water based, volume reduction process in which contaminants are extracted and concentrated into a small residual portion of the original volume using physical and chemical means. The principal process involves transfer of the contaminants from the sediment to the wash water and their subsequent removal from the water. The small volume of contaminated residual concentrate is then treated by destructive or immobilizing processes. By changing steps in the process, soil washing may be made amenable to a variety of site characteristics. Chemical extraction involves removing contaminants from sediment by dissolution in a solvent that is later recovered and treated. A variety of chemical extraction processes exist and they employ a number of solvents. Solvents are chosen based on contaminant solubility and on whether the contaminant is organic or inorganic. Chemical extraction processes include CF Systems Organic Extraction Process and Resources Conservation Corporation's Basic Extraction Sludge Treatment (BEST). 9-1 ------- DEFINITION OF EXTRACTION The use of solvents to separate contaminants from solvents. ADVANTAGES Volume reduction LIMITATIONS Contaminants are not destroyed. Not a stand-alone technology. 9-2 ------- EXTRACTION \ Soil Washing Chemical Extraction DEFINITION OF SOIL WASHING A water-based process for mechanically scrubbing soils to remove undesirable contaminants. MECHANISMS FOR REMOVING CONTAMINANTS Dissolving or suspending them in the wash solution Concentrating them into a smaller volume of soil through particle size separation techniques. 9-3 ------- APPLICABILITY OF SOIL WASHING ON ORGANIC CONTAMINANTS Sandy/ Sitty/Clay Gravelly Soils Soils Hatogenated volatiles 2 1 Hatogenated semivolatiles 1 1 Nonhatogenated semivolatiles 2 1 RGBs 1 1 Pesticides (hatogenated) 1 1 Dtoxins/Furans 1 1 Organic cyanides 1 1 Organic corrosives 1 1 2 - Good to Excellent Applicability; 1 - Moderate to Marginal Applicability; 0 - Not Applicable APPLICABILITY OF SOIL WASHING ON INORGANIC & REACTIVE CONTAMINANTS Sandy/ Silty/Clay Gravelly Soils Soils Volatile metals Nonvolatile metals Asbestos Radioactive materials Inorganic corrosives Inorganice cyanides Oxidizers Reducers 2 1 2 1 0 0 1 1 1 1 1 1 1 1 1 1 2 - Good to Excellent Applicability; 1 - Moderate to Marginal Applicability; 0 - Not Applicable KEY PHYSICAL PARAMETERS Particle Size Distribution >2mm 0.25 - 2 mm 0.063 - 0.25mm < 0.063mm Moisture Content Pre-treatment required Effective Soil Washing Limited Soil Washing Difficult Soil Washing 9-4 ------- KEY CHEMICAL PARAMETERS Organics - concentration volatility partition coefficient Metals Humic Acid SOIL WASHING APPLICABLE PARTICLE SIZE RANGE Clay . Silt , Sand 1001 LH 1 Gravel Stone 50 III increasing particle size LIMITATIONS Silt/Clay Hydrophobic Contaminants Mixtures 9-5 ------- AQUEOUS SOIL WASHING PROCESS VOIMfbs ComamkuMd Sol Trtattd Air Emissions M*»tpW«lsc Extracting Agsnt(i) (Surt«cunt«.»1c.) Sol | Soil Preparation (1) SludgtV Denominated Fines Ov«tslz»d Rsjscts DEFINITION OF CHEMICAL EXTRACTION An organic solvent-based process for separating contaminants from soils. E EFFECTIVENESS OF XTRACTION ON ORGANIC Treatability Groups Halogenated volatiles Halogenated semivolatiles Nonhalogenated volatiles Nonhalogenated semivolatiles PCBs Pesticides (halogenated) Dtoxins/Furans Organic cyanides Organic corrosives SOLVENT CONTAMINANTS Effectiveness 1 1 1 1 2 1 1 1 1 2 - Good to Excellent Applicability; 1 - Moderate to Marginal Applicability; 0 - Not Applicable 9-6 ------- EFFECTIVENESS OF SOLVENT EXTRACTION ON INORGANIC & REACTIVE CONTAMINANTS Treatability Groups Volatile metals Nonvolatile metals Asbestos Radioactive Materials Inorganic corrosives Inorganic cyanides Oxidizers Effectiveness 0 0 0 0 0 0 0 2 - Good to Excellent Applicability; 1 - Moderate to Marginal Applicability; 0 - Not Applicable LIMITATIONS Metals Residual Solvent Solvent Selection SOLVENT EXTRACTION PROCESS t *. Emb * Co %$* I » Treated Emissions 4 Recycled Solvent (4) | Excavate 1 fc Waste (1 ) 1 k * Preparation I ' Extr^or I , Separator 1 (3) 1 nr**h'e L^Concentrafed ContSnts Contaminants (5) 9-7 ------- r CF SYSTEMS Solvent - liquified hydrocarbon gases Pumpable slurry <1/8" particle diameter CF SYSTEMS ORGANIC EXTRACTION SYSTEM Compressor Recycled Solvents Solvents and Organics Solvent l actor 1 »» Separator Solvent Recovery Still ^f^ 1 \ i Solids and Water Solid/Liquid Separator Solids Water Resources Conservation Corporation's BASIC EXTRACTION SLUDGE TREATMENT (BEST) Solvent - aliphatic amines Batch operation <1" particle diameter 9-8 ------- PCB SAMPLES TESTED IN RCC's LABORATORY Raw Sample River Sediment "B" Superfund B (#13) Harbor Sediment "B" Harbor Sediment "C" Harbor Sediment "D" Harbor Sediment NB-A Harbor Sediment NB-B PCB (mg/kg) 960 83 20,000 30,000 430 5,800 16,500 Phase Composition Oil% Water % Solids % 26 44 3 5.6 0.38 1.9 4.3 17 40 22 62 47 69 51.6 83 16 75 32 53 29 44.1 PCB SAMPLES TESTED IN RCC's LABORATORY River Sediment "B" Superfund B (#13) Harbor Sediment "B" Harbor Sediment "C" Harbor Sediment "D" Harbor Sediment NB-A Harbor Sediment NB-B PCBs Oil (mg/kg) N/A N/A 970,000 550,000 N/A 280,000 360,000 in Product Fraction Water (mg/kg) N/A N/A <.006 N/A N/A <.005 <.005 Solids (mg/kg) 40 1.0 27 94 32 35 75 % Removal 96.5% 99.8% 99.9% 99.9% 96.0% 99.4% 99.8% OTHER CHEMICAL EXTRACTION TECHNOLOGIES Extralesol Low Energy Extraction Process (LEEP) 9-9 ------- Thermal Technologies (Incineration, LT Desorption, Recovery Systems) Dr. George Hytantis International Waste Management Systems Knoxvile, Tennessee As a result of the increased awareness surrounding the proper management of hazardous waste disposal and cleanup from a future liability standpoint, the use of thermal technologies for the treatment of contaminated sediments is supplanting other remedial actions, most notably land disposal. The lack of sufficient cost and performance information on other promising treatment technologies, such as various biotreatment technologies, has also contributed to the popularity of well-established, yet often costly thermal treatments for the destruction of hazardous wastes. Types of processes used to thermally remediate soils and sediments include rotary kiln incineration, pyrolysis, infrared incineration, circulating bed combustion, and low temperature thermal desorption. Ideally, the ultimate goal of thermal combustion is to convert waste materials into benign end-products (CO2, H2O vapor, SO2, NOX, HCL, and ash) using high temperature oxidation under controlled conditions. The suitability of contaminated sediments for the application of thermal treatment processes is determined by the physical and chemical makeup of the material and by the volume to be treated. These characteristics impact: 1. The extent of screening required. 2. The amount of dewatering required and the selection of a dewatering method. 3. The type of thermal treatment utilized. 4. * Air pollution control system design. 5. Treatment of residual ash prior to final disposal. The applicability of a number of thermal processing methods on sediments have already been demonstrated in private and government sponsored cleanups. Although incineration and other thermal technologies have been shown to be among the most effective treatment technologies for hazardous and toxic waste destruction, costs tend to be high due to the intensive energy requirements and subsequent disposal of ash and slag. 10-1 ------- RANGE OF CURRENT COST FOR ROTARY KILN INCINERATION Volume(CY) Cost ($ PER CY) <6750 6950-20250 20250-40500 >40500 675-2025 405-1215 270-810 135-540 UNIT COST ESTIMATES FOR STEPS INVOLVED IN TREATMENT AND OF DISPOSAL OF PCB-CONTAMINATED SEDIMENTS Operation Cost ($ PER CY) Dredging Transport Storage Redeposition 15 10-96 8 25-375 Afterburner Rotary Kiln and an Afterburner. 10-2 ------- Pyrolysis Schematic Infrared Incineration Process Flow Diagram STACK COMBUSTOR Circulating Bed Combustor Schematic 10-3 ------- Bioremediation Dr. Carol D. Litchfield Foster Wheeler Enviresponse, Inc. Livingston, NJ Bioremediation is a complex process that converts organic contaminants into microorganism biomass and simpler, "waste" substances. In complete conversion the waste products are harmless metabolic by-products, such as CO2, CH4, water, and inorganic salts. In incomplete conversion the waste products are organic compounds that are simpler than the original contaminants and that are hopefully less toxic. In most cases, bacteria and/or fungi are the principle types of organisms involved in bioremediation. The rate and completeness of bioremediation processes may be improved in four ways: enhancement of the degradative potential of the natural microbial assemblages through nutrient and electron acceptor addition; introduction of specially selected microbial strains with distinctive degradative capacities; application of enzymes; and vegetative uptake. Enhancement of the natural microbial assemblages is the most commonly used bioreme- diation technique. The rate of biodegradation may often be limited by the bioavailability of the contaminants and the presences of heavy metals. Sediment properties which impact bioavailability influence the interaction between sediment and contaminants. These properties include type and amount of clay, cation exchange capacity, organic matter content, pH, oxidation-reduction conditions, and the conductivity of the water. Pre-treatments which may increase the bioavailability of contaminants include grinding to increase the surface area, adding a bulking material, and soil washing. Heavy metals may often be removed through pre-treatment methods; biosorption of metals using bacterial or algal cells is one possible method. The biodegradation of contaminated sediments can be done in two ways: biotreatment after dredging the polluted sediments from the waterway or leaving the sediments in place and treating in situ. Dredging allows four types of biological treatment processes: composting, bioslurries, solid phase treatment, and land-farming. Composting involves the storage of the target sediment with a bulking agent, such as hay or wood chips. Bioslurries require the production of a slurry which is then treated in a bioreactor in orderto maintain intimate mixing of the sediment with the microorganisms. In solid phase treatment, the dredged materials are placed in treatment cells and moisture and nutrients controlled through mixing and nutrient application. In land-farming, the dredged materials are mixed with surface soils to a depth of six to nine inches by placing the dredged material on the soil surface and then tilling. The area may potentially be farmed if the contaminant levels are reduced to safe levels. In situ bioremediation is the enhancement of naturally occurring biodegradative processes. It relies on the addition of nutrients and an electron acceptor to increase the rate of degradation. If oxygen is to be added as the electron acceptor, the amounts of iron and manganese present in the sediment are important considerations. To date, most of the work on the bioremediation of sediments has involved bench scale treatability studies. Rates for bioremediation in the field will likely be slower than in the laboratory where conditions can be optimized. 11-1 ------- THE BIOREMEDIATION PROCESS Organic Contaminant + Action of Fungi and Bacteria Microorganism Biomass + Harmless Byproducts (C02, CH4, salts) ORGANISMS CAPABLE OF BIOREMEDIATION Obligate Anaerobic Bacteria (Clostridium, Desulfovibrio, Methanogens Consortium) Heterotrophic Aerobic Bacteria (Pseudomonas Arthrobacter, Acinetobacter, Micrococcus, Achromobacter) Photosynthetic Bacteria (Chromatium, Rhodopseudomonas, Athiorhodaceae) Oligotrophic Bacteria (Cautobacter, etc.) Algae (Chlorella, etc.) Cyanobacteria (Blue - Green Algae) Actinomycetes (Nocardia, Mycobacterium) Fungi (Fusarium, Aspergillus, Penicillium) COMPOUNDS SUSCEPTIBLE TO BIOREMEDIATION CLASSES OF CONTAMINANTS Halogenated and Nonhatogenated Alphatics Halogenated and Nonhatogenated Aromatics Polycyclic Aromatics Halogenated Polycyclic Aromatics Pesticides Nitrosamines Phthalate Esters Nitro and Chlorophenols PRIORITY POLLUTANT EXAMPLE Methylene Chloride Chlorobenzene Anthracene 2-Chloronaphthalene Dieldrin N-Nitrosodiphenylamine Bis (2-Ethylhexyl) Phthalate Pentachlorophenol 11-2 ------- DETERMINANTS OF THE RATE OF MICROBIAL BIOREMEDIATION 1. Presence of microorganisms 2. Availability of nutrients 3. Availability of contaminants 4. Redox conditions 5. Water activity 6. Environmental factors. METHODS OF BIOREMEDIATING REMOVED SEDIMENTS 1. Composting 2. Bioslurries 3. Solid Phase Treatment 4. Land Farming. SOLID PHASE BIOREMEDIATION Pre-Treatment Sediment Screening Oversized Material to Special Handling Solid-Phase Treatment 11-3 ------- SOLID PHASE BIOREMEDIATION Treatment Perforated Drain Pipe Solid-Phase Treatment Sediment Layer / / /Compacted Clay/ Sprinkler System IMPORTANT SITE CHARACTERISTICS FOR IN SITU BIOREMEDIATION 1. Characteristics 2. Microorganisms present and their capability to degrade the contaminants 3. Type of contaminant 4. Bioremediation products 5. Depth, profile, and areal distribution of constituents in the sediments 6. Sediment properties for biological activity 7. Sediment characteristics 8. Hydrodynamics of the site TYPES OF IN SITU BIOREMEDIATION APPROACHES 1. Enhancement of the natural bioremediative potential 2. Introduction of exogenous, specialized microorganism application 11-4 ------- TWO-STEP COMBINED ANAEROBIC/ AEROBIC PROCESS TO BIOREMEDIATE HALOGENATED ORGANICS anaerobic bacteria aerobic bacteria cells C02 + H2O ENHANCEMENT EXAMPLES 1. Increasing the sediment's dissolved oxygen levels. 2. Providing alternative electron acceptors. 3. Mixing the sediments to improve bacterial access to contaminants. MICROBIAL CHARACTERISTICS TO BE CONSIDERED PRIOR TO USING EXOGENOUS ORGANISMS 1. Ability of the microorganisms to survive in a foreign environment. 2. Ability of the microorganisms to move through- out the contaminated site. 3. Ability of the microorganisms to retain their activity. 4. Assurance that the microorganisms are non- pathogenic to humans and the ecosystem. 11-5 ------- Solidification/Stabilization Mr. Ed Barth Mr. Tommy E. Meyers U.S. Environmental Protection Agency U.S. Army Corps of Engineers Cincinnati, Ohio Vicksburg, Mississippi Solidification/stabilization, as a type of containment technology, immobilizes and/or isolates contaminated sediments. Solidification/stabilization refers to the use of additives or processes to transform hazardous waste into a more manageable or less toxic form. Solidification/stabilization functions both physically and chemically. Solidification is a physical process which refers to the conversion of a liquid or semi-solid to a solid, resulting in a substantial reduction of surface area and, thus, contaminant leaching. Solidification is considered an effective process in the immobilization of both metals and inorganics. Stabilization is a chemical process which refers to the alteration of the chemical form of contaminants. Generally, stabilization is considered an effective process in the immobilization of metals, but not organics. In fact, organics may actually interfere with solidification/stabilization setting reactions. The applicability of solidification/stabilization processes to the sediments of concern is determined by chemical and physical analysis. Several leach tests are available for this purpose. Listed wastes requires the Toxicity Characteristics Leaching Procedure (TCLP). Additional leaching tests may be chosen from American National Standards Institute (ANSI) procedures appropriate for the contaminant. Newer procedures, such as the Standard Batch Leachate Test (SBLT), are constantly being reviewed and accepted according to the need or circumstance. Physical testing, aimed at such product characteristics as bearing capacity, trafficability, and permeability, is accomplished through established engineering tests. For example, ratios of waste to binder in each system are evaluated using the Unconfined Compressive Strength (UCS) Test. Bulk density, permeability, and moisture content are also commonly tested to determine the degree of solidification/stabilization. Solidification/stabilization applications to contaminated sediments include: 1. Marathon Battery Company site in the Village of Cold Spring, New York. 2. The Upper Acushnet River Estuary in New Bedford, Massachusetts 3. The navigation channel at Indiana Harbor, Indiana. 4. Buffalo River sediment, New York. 5. Halby Chemical site in Wilmington, Delaware. Solidification/stabilization has been tested at the bench-scale level or better at these sites. Contaminants ranged from organics, including PCBs, to metals, including cadmium, cobalt, nickel, lead, copper, chromium, and arsenic. 12-1 ------- WHY USE S/S? Water Content Shear Strength Need to t shear strength I compressibility I permeability for land disposition 200-300% (slurry) 0 MODEL OF CONVECTIVE TRANSPORT (CT) TO DIFFUSIVE TRANSPORT (DT) II CT DT III L- P o s IV D 1/2 IMPORTANT RATIOS Binder Waste Water Total Solids .1-.5 .4 12-2 ------- COSTS Binder 30% Solids: 2000 Ibs x .3 = 600 Ibs solids 10%BS: 600 Ibs x .1 60 Ibs binder $50/T = $.025/lb: 60 Ibs x .025/lb = $1.50 Labor Handling Equipment SLT Plot cumulative release with time Compare to WQC Each step represents x pore volumes GRAIN SIZE DISTRIBUTION MASS CLAY SILT SAND GRAVEL GRAIN SIZE 12-3 ------- DISTRIBUTION OF METALS IN SIZE FRACTIONS r As Pb Cd Cr Cu Hg Zn Coarse 1.0 3.2 .06 4.8 3.7 0.17 17 Mixed Fine 1.1 111 7.0 447 .51 13 4.6 452 3.0 385 0.14 13 12 1920 (from Rizkaliah) SEDIMENT SHEAR STRENGTH no montmorillinite low organic content Binder FA (2-10%) L(2-10%) C(2-10%) C/FA(2-10%) Shear Strength (undrained) <10KN/m 10KN/m high high (from Rizkaliah} MARATHON BATTERY SEDIMENTS 32000 CY 24% Solids pH 6.6-6.8 EP TOX ASTM G21 ASTM G22 12-4 ------- MARATHON Raw Vendor Vendor Vendor Vendor BATTERY S/S EP TOX (mg/l) Cji C_s Eb_ .01 .01 .14 .01 .02 .10 0.1 .02 .02 0.08 .13 .29 RESULTS M .53 .88 .21 1.3 B. R. SEDIMENTS (jig/g) O&G 9100 TOC 21,400 Zn 151 Pb 81 PAH 5.9 mg/l B. R. S/S RESULTS T UCS with time (>50 psi) t Cr, Cu in TCLP i Pb, Ni, An in TCLP Cr, Cu, Pb, Ni below WQC in SLT no conclusion on PAHs 12-5 ------- INDIANA HARBOR S/S RESULTS As, Pb, Cr, Zn leaching decreased in SLT Fly ash, lime did not reduce leaching 12-6 ------- Residual Disposal Methods (Confined Disposal Methods, Capping and Landfills) Dr. Robert P. Gambrell and Dr. William H. Patrick, Jr. Laboratory for Wetland Soils and Sediments Louisiana State University Baton Rouge, Louisiana Disposal alternatives for dredged material consist of unrestricted and restricted options. Most dredged materials are the product of maintenance dredging; the majority of this material is not contaminated and is thus suitable for unrestricted disposal. Unrestricted alternatives include unrestricted open-water disposal ("dumping"), sanitary landfills, and beneficial uses. Restricted alternatives suitable for contaminated sediments include capping, confined disposal facilities (CDF), and hazardous landfills. Pre-testing is essential in deciding on a particular restricted alternative and on the proper design of that alternative. The principal concept for reducing long-term environmental effects associated with open water disposal is to "cap" (cover or encapsulate) the contaminated material with clean dredged material. Contaminated sediments can be capped with clean sediments in situ, or they can be dredged, moved, and then capped. By keeping contaminated sediment in the waterway, stable geochemical and geohydrologic conditions are maintained in the sediment, minimizing release of contaminants to surface water, ground water, and air. Placement of a clean cap or cover on top of the contaminated sediment reduces diffusion and convection of contaminants into the water column and prevents bioperturbation or uptake by aquatic organisms. Capping could also be considered for disposal of residual solids from treatment or pre-treatment processes. Capping options include level bottom capping and contained aquatic disposal (CAD). Capping techniques may not be suitable for the most highly contaminated sediments. They may be favorable in some applications because of ease of implementation, lack of upland requirements, comparatively low cost, and highly effective contaminant containment efficiency. The principal disadvantages for open water disposal options are the concern for long term stability and effectiveness of the cap and the complications that may occur if remediation of the disposal site should be required in the future. Capped sites require monitoring and maintenance to ensure site integrity. CDFs are engineered structures enclosed by dikes and designed to retain dredged material. They may be located upland (above the water table), partially in the water near shore, or completely surrounded by water. The primary goal of CDF design is minimization of contaminant loss. Contaminants are potentially lost via leachate through the bottom of the CDF, seepage through the CDF dikes, volatilization to the air, and uptake by plants and animals living or feeding in the CDF. A variety of linings have been used to prevent seepage through the dike walls. The most effective are clay or bentonik-cement slurries, but sand, soil, and sediment linings have also been used. Caps are the most effective way to minimize contaminant loss from CDFs through contaminant volatilization and plant and animal uptake. Offsite landfills may be considered for highly contaminated material or for treated residuals. There are two types of landfills: sanitary and hazardous. Highly contaminated sediments or sediment wastes may be inappropriate for sanitary landfills and must be disposed of in hazardous landfills, which will add greatly to total treatment cost. Because dredging often results in large quantities of dredged material with high water contents, dredging may not be compatible with landfill disposal. Large quantities of dredged material and high water content both increase the volume of material the landfill must accommodate and thus drive up costs. If use of a landfill is required .then specific pre-treatment options (such as dewatering) and/or treatment options may have to be considered. 13-1 ------- DISPOSAL OF DREDGED MATERIAL, CONTAMINATED SEDIMENTS, AND TREATED SEDIMENTS R.P. Gambrell W.H. Patrick, Jr. Laboratory for Wetland Soils and Sediments Louisiana State University Baton Rouge, Louisiana Disposal alternative for contaminated sediments refer to the various possible placement options to minimize contaminant release. Disposal alternatives apply to: 1. Untreated dredged sediments 2. Sediments treated to remove contaminants 3. Sediments treated to immobilize contaminants 13-2 ------- DISPOSAL OPTIONS 1. Restricted 2. Unrestricted RESTRICTED OPTIONS 1. Capping 2. Confined Disposal Facility 3. Landfill 4. Disposal site selection and management to maintain a contaminant immobilizing environment. UNRESTRICTED OPTIONS 1. Open water disposal 2. Sanitary landfills 3. Beneficial uses 13-3 ------- CAPPING Covering or encapsulating contaminated sediments, usually in deep, quiescent water, with clean dredged material to isolate and immobilize contaminants. Capping may be applicable to contaminated sediments in situ, but it is more often implemented after contaminated sediments have been dredged and transported to a disposal site. ADVANTAGES TO CAPPING: 1. Reduced transport of dredged material. 2. Sometimes applicable in situ. 3. Contaminated sediments are maintained in a biogeochemical environment that favors contaminant immobilization. 4. Contaminated sediments are isolated from significant diffusive losses or contact with benthic organisms. 5. Expensive upland disposal sites may not be required. IMPORTANT CAPPING CONSIDERATIONS: 1. Current velocity 2. Water depth 3. Salinity and temperature stratifications 4. Bathymetry (bottom contours) 5. Dispersion and mixing 6. Navigation and other location factors (Culinane, etal., 1989) 13-4 ------- VARIANTS OF CAPPING: 1. Level bottom capping employs stable mound- ing of contaminated dredged material which can then be covered with clean sediments. 2. Contained aquatic disposal (CAD) employes an exisiting depression, excavation of a subaqueous disposal pit, or construction of submerged confining dikes (Palermo et al., 1989). ' SUBAQUEOUS DISCHARGE METHODS. 1. Minimizes potentially adverse impacts of capping 2. Increases placement accuracy (Averett et al., 1990) LEVEL BOTTOM CAPPING 13-5 ------- CONTAINED AQUATIC DISPOSAL DERRICK DISCHARGE WATER SURFACE LINE ^^ =N.« «\ I ^^-SUBMERGED DIFFUSER JL. ^-ICLEAN SAND, ETC.) CAPPING CONCERNS 1. Long-term stability and effectiveness of the cap 2. Difficulties if future remediation of the disposal site is required (Averett et al., 1990) 3. Maintenance and long-term monitoring may be required (Palermo et al., 1989) CONFINED DISPOSAL FACILITY (CDF): CDFs are structures designed to retain dredged material. Their primary function is to minimize contaminant losses. 13-6 ------- CDF CONSTRUCTION: Large cells enclosed by dikes Smaller cells or multiple cells may be used for separating water Linings are designed to minimize contaminant loss by seepage (clay and bentonite-cement linings are most effective, but soil, sediment, and synthetic linings have been successfully used). CDF LOCATION: 1. Upland (above water table) 2. Near shore partially within water table zone 3. Island in a water body POSSIBLE ROUTES OF CONTAMINANT LOSS FROM A CDF: 1. Vertical seepage through bottom 2. Lateral seepage through dikes 3. Volatilization 4. Uptake by plants and animals (Garbaciak, 1990; Miller, 1990) 13-7 ------- Capping a CDF with clean sediment or another liner material will minimize uptake losses and may reduce volatilization losses. TYPES OF LANDFILLS: 1. Sanitary 2. Hazardous waste LIMITATIONS OF HAZARDOUS WASTE LANDFILLS FOR DREDGED MATERIAL DISPOSAL: 1. High costs 2. Available capacity limited for typical large volume dredging projects 3. Dewatering and other pre-treatments may be required. 13-8 ------- CONSIDERATIONS FOR SELECTING DISPOSAL ALTERNATIVES FOR CONTAMINATED SEDIMENTS 1. The kinds and amounts of contaminants present. 2. Physical, chemical, and biological characteristics of the dredged sediments. 3. The particular risk represented by the contaminants. 4. The disposal options available based on technological, economic, regulatory and environmental considerations. 5. The environmental chemistry and fate of the contaminants under conditions of the various disposal alternatives. MAJOR DISPOSAL ALTERNATIVES: A. Subaqueous Placement B. Application to Intertidal Sites for Disposal or Productive Use C. Upland Application SUBAQUEOUS DISPOSAL A. Disposal not in conflict with important economic or ecological productivity 1. Confined Disposal a. Stable mounding with option for capping b. Confined in a depression, constructed pit, or by underwater berms with capping 2. Unconfined - wide dispersal with apparent loss from disposal area B. Application to important ecological zones. 13-9 ------- APPLICATION TO INTERTIDAL SITES A. Habitat development 1. Confined by boundary structure - resistant to erosion 2. Unconfined - some erosion and some consolidation (i.e., mudflat, marsh or island construction or enhancement) B. Non-biological purposes 1. Shoreline stabilization, modification 2. Confined by boundary structure UPLAND APPLICATION A. Long-term confinement for disposal purposes B. Interim confinement C. Unconfined upland D. Habitat development E. Agricultural soil amendment and land reclamation F. Use for fill and other construction or engineering purposes. MANAGEMENT PRACTICE APPLICABLE TO DISPOSAL ALTERNATIVES Scheduling to coincide project with the least sensitive portions of the life cycle of potentially affected organisms. Applicable to subaqueous, intertidal. Covering with uncontaminated material (capping). Applicable to subaqueous, intertidal, upland. 13-10 ------- MANAGEMENT PRACTICE APPLICABLE TO DISPOSAL ALTERNATIVES (cont.) Use of confinement structures to minimize dispersion and transport by erosion and currrents. Applicable to subaqueous, intertidal, upland. Pre-treatment to remove or immobilize contaminants prior to long-term disposal or use. Applicable to subaqueous, intertidal, upland. MANAGEMENT PRACTICE APPLICABLE TO DISPOSAL ALTERNATIVES (cont.) Managing plant and animal populations to reduce uptake. Applicable to intertidal, upland. Reducing suspended solid loads in effluents. Applicable to subaqueous, intertidal, upland. Reducing leaching losses. Applicable to intertidal, upland. ftU.S. GOVERNMENT PRINTING OFFICE;! 991 -5i»8 -187/ 25606 13-11 ------- |