PTI ENVIRONMENTAL Innovative Approaches to Environmental Assessment and Regulatory Decision-Making in Puget Sound: Potential Applications to Ocean Discharge Permitting Prepared for U.S. Environmental Protection Agency Office of Wetlands, Oceans, and Watersheds Washington, DC September 1991 ------- PTI ENVIRONMENTAL SERVICES 15375 SE 30th Place Suite 250 Bellevue, Washington 98007 Innovative Approaches to Environmental Assessment and Regulatory Decision-Making in Puget Sound: Potential Applications to Ocean Discharge Permitting Prepared for U.S. Environmental Protection Agency Office of Wetlands, Oceans, and Watersheds Washington, DC EPA Contract No. 68-D8-0085 PTI Contract C744-37 September 1991 ------- CONTENTS Page LIST OF FIGURES v LIST OF TABLES vi LIST OF ACRONYMS vii EXECUTIVE SUMMARY viii 1. INTRODUCTION 1 1.1 BACKGROUND 1 1.2 OBJECTIVE 4 1.3 REPORT OVERVIEW 6 2. PUGET SOUND REGULATORY PROGRAMS 9 2.1 COMMENCEMENT BAY SUPERFUND INVESTIGATIONS 9 2.2 PUGET SOUND DREDGED DISPOSAL ANALYSIS PROGRAM 11 2.3 WASHINGTON STATE'S SURFACE WATER QUALITY STANDARDS 12 2.4 WASHINGTON STATE'S SEDIMENT MANAGEMENT STANDARDS 13 2.5 PUGET SOUND ESTUARY PROGRAM 15 2.6 WASHINGTON STATE'S MODEL TOXICS CONTROL ACT 17 3. SEDIMENT AND WATER QUALITY ASSESSMENT TOOLS 18 3.1 SEDIMENT QUALITY ASSESSMENT TOOLS 18 3.1.1 Sediment Quality Assessment 18 3.1.2 Biological Indicators 21 ii ------- 3.2 WATER QUALITY ASSESSMENT TOOLS 25 3.2.1 Water Quality Criteria 25 3.2.2 Whole-Effluent Toxicity Testing 26 3.2.3 Monitoring of Wastewater Particulate Material 28 3.2.4 Establishment of Site-Specific, Surface Water Cleanup Levels Protective of Human Health 29 4. MODELING TECHNIQUES 32 4.1 CONTAMINANT TRANSPORT AND FATE MODELING 32 4.1.1 Modeling the Relationship Between Contaminant Source Loading and Accumulation of Contaminants in Sediments 33 4.1.2 Modeling of Sediment Recovery Processes 39 4.2 HUMAN HEALTH RISK ASSESSMENT MODELING 44 4.2.1 Commencement Bay Superfund Investigations 46 4.2.2 Puget Sound Dredged Disposal Analysis Program 48 4.3 ECOLOGICAL RISK ASSESSMENT MODELING 50 4.3.1 Harbor Island Superfund Site 51 4.3.2 METRO'S Toxic Sediment Remediation Project 52 4.3.3 PSDDA's Evaluation of Dredged Material Disposal Options 53 5. MONITORING GUIDANCE 55 5.1 EXPANDED MONITORING REQUIREMENTS FOR MAJOR NPDES DISCHARGES 55 5.2 PUGET SOUND PROTOCOLS 56 5.3 WASHINGTON DEPARTMENT OF ECOLOGY'S PERMIT WRITERS MANUAL 58 6. DECISION-MAKING FRAMEWORKS 60 6.1 COMMENCEMENT BAY SUPERFUND INVESTIGATIONS 60 6.1.1 Characterizing Problem Areas 62 6.1.2 Ranking Problem Areas and Problem Chemicals 64 6.1.3 Technical Approaches Developed for Site Management 66 iii ------- 6.2 PUGET SOUND DREDGED DISPOSAL ANALYSIS PROGRAM 67 6.2.1 Tier 1 - Review of Existing Information 70 6.2.2 Tier 2 - Chemical Testing 70 6.2.3 Tier 3 - Biological Testing 72 6.3 WASHINGTON STATE'S SURFACE WATER QUALITY STANDARDS 75 6.4 WASHINGTON STATE'S SEDIMENT MANAGEMENT STANDARDS 77 6.4.1 Sediment Quality Standards 77 6.4.2 Sediment Source Control Standards 78 6.4.3 Sediment Cleanup Standards 82 6.5 PUGET SOUND ESTUARY PROGRAM 83 6.6 WASHINGTON STATE'S MODEL TOXICS CONTROL ACT 84 7. APPLICABILITY OF PUGET SOUND APPROACHES TO SECTION 403 87 7.1 COMMON ELEMENTS OF THE PUGET SOUND REGULATORY PROGRAMS 87 7.2 APPLICATIONS OF PUGET SOUND APPROACHES TO SECTION 403 DETERMINATIONS 89 7.2.1 Determinations of No Irreparable Harm 90 7.2.2 Determinations of No Unreasonable Degradation 93 REFERENCES 99 iv ------- LIST OF FIGURES Page Figure 1. Section 403 decision-making process 2 Figure 2. Hypothetical site of a wastewater discharge 35 Figure 3. Model domains for impact zone analysis 37 Figure 4. Three-dimensional view of the impact zone model 38 Figure 5. Schematic of processes controlling chemical concentrations in surface sediments 41 Figure 6. Three-dimensional view of the sediment recovery zone model 45 Figure 7. Evaluation of contaminant source status, source control, and natural recovery in the selection of remedial alternatives for Commencement Bay 68 Figure 8. PSDDA three-tiered decision-making approach 69 Figure 9. Summary of biological testing requirements 73 Figure 10. Section 404 and Section 401 disposal guidelines 74 Figure 11. Process for evaluating the need for sediment impact zones 80 Figure 12. Correspondence between Puget Sound technical approaches and Section 403 ocean discharge criteria 94 v ------- LIST OF TABLES Page Table 1. List of ocean discharge criteria 3 Table 2. Hypothetical example of action assessment matrix 63 Table 3. Summary of ranking criteria for sediment contamination, toxicity, and biological effects indicators 65 Table 4. Biological effects criteria for Puget Sound marine sediments 79 vi ------- LIST OF ACRONYMS ADI acceptable daily intake AET Apparent Effects Threshold AKART all known, available, and reasonable methods of prevention, control, and treatment ANCOVA analysis of covariance ANOVA analysis of variance BMP best management practice CCMP Comprehensive Conservation and Management Plan CERCLA Comprehensive Environmental Response, Compensation and Liability Act CORMIX Cornell Mixing Zone Expert System Corps U.S. Army Corps of Engineers CWA Clean Water Act CZMP Coastal Zone Management Plan DNR Washington Department of Natural Resources EAR elevation above reference Ecology Washington Department of Ecology EP equilibrium partitioning EPA U.S. Environmental Protection Agency EXAMS Exposure Analysis Modeling System METRO Municipality of Metropolitan Seattle ML maximum level MTCA Model Toxics Control Act NPDES National Pollutant Discharge Elimination System PAH polycyclic aromatic hydrocarbon PCB polychlorinated biphenyl PSAMP Puget Sound Ambient Monitoring Program PSDDA Puget Sound Dredged Disposal Analysis PSEP Puget Sound Estuary Program PSWQA Puget Sound Water Quality Authority QA/QC quality assurance and quality control RI/FS remedial investigation and feasibility study ROD record of decision SEDCAM sediment contaminant assessment model SIZ sediment impact zone sizmax sediment impact zone maximum criteria SL screening level SQS sediment quality standards TI/RE toxicity investigation/reduction evaluation TMDL total maximum daily load WAC Washington Administrative Code WASP4 Water Quality Analysis Simulation Program 4 WLA wasteload allocation vii ------- EXECUTIVE SUMMARY BACKGROUND Under the authority of the Clean Water Act (CWA), the U.S. Environmental Protection Agency (EPA) or delegated states issue National Pollutant Discharge Elimination System (NPDES) permits for the discharge of pollutants from point-sources into navigable waters, providing the discharge meets all applicable requirements of the law. Section 403 of the CWA identifies requirements for the permitting of point-source discharges to the territorial sea, the contiguous zone, and the oceans. The current Section 403 regulations (40 CFR 125 Subpart M) require a determination that a point-source discharge will not cause unreasonable degradation of the marine environment. A determination of no unreasonable degradation can be made through the use of 10 ocean discharge criteria specified in the regulations. Such determinations require a substantial amount of site-specific data, because consideration must be given to a multitude of potential effects of the discharge on the receiving environment. In the absence of sufficient data to make such a determination, a Section 403 permit can still be issued subject to additional conditions, as long as it can be determined that the permitted discharge will not cause irreparable harm to the marine environment. For Section 403 permits issued on the basis of a determination of no irreparable harm, additional monitoring will be required under the permit so that the determination of no unreasonable degradation can be made at some time in the future. EPA Headquarters is currently undertaking a number of supporting activities designed to ensure effective implementation of Section 403, including development of nationally consistent technical and procedural guidance. It is expected that the guidance being developed by EPA will integrate the evaluation criteria specific to Section 403 with the evolving water quality-based toxics control approach for marine waters. While the current water quality-based toxics control approach emphasizes effluent testing and compliance with water quality criteria and standards, Section 403 evaluations will also include assessment of in situ biological impacts (U.S. EPA 1990). It is expected, therefore, that the guidance developed by EPA will include monitoring requirements using such evaluation tools as sediment toxicity tests, benthic community surveys, and assessments of bioaccumulation. Hence, integration of the water quality-based toxics control approach with the Section 403 evaluation criteria should achieve a more comprehensive degree of environmental protection than could be achieved with either approach alone. REGULATORY PROGRAMS IN PUGET SOUND Regulatory programs currently being applied to the management of point-source discharges, the disposal of dredged material, and the cleanup of contaminated sediments in Puget Sound, Washington, have incorporated various innovative approaches to the assessment of impacts of pollutants on the receiving environment. It is expected that some of these innovative approaches may be applicable to assessments that will be conducted as part of Section 403 permit reviews. ------- The objective of this report is to describe the various regulatory programs currently being applied in Puget Sound, as well as the technical approaches used in those programs to assess pollutant impacts on the receiving environment. This report focuses on those assessment techniques that are potentially applicable, either directly or with minor modification, to the types of assessments required for the issuance or reissuance of Section 403 permits. By documenting technical approaches applied in Puget Sound regulatory programs as case studies, it is anticipated that elements of those approaches that show particular promise can be incorporated into the technical approach later proposed for implementation of Section 403. Whereas historical efforts to regulate pollutant inputs to Puget Sound were primarily discharge-oriented, and, at least initially, focused on the effects of conventional pollutants (e.g., oxygen-depleting substances, suspended solids, fecal coliform bacteria, pH, and oil and grease), there is now an increasing awareness that the remaining threats to the Puget Sound ecosystem are related primarily to toxic, and not conventional, pollutants. Also, because of the laiown affinity of many toxic pollutants for particulate matter, it is generally believed that many of the adverse effects associated with toxic pollutants from point-sources in Puget Sound occur as a result of sediment contamination. Consequently, the focus of most of the regulatory programs concerned with pollution in Puget Sound is now on contaminated sediments and their effects on the ecosystem. This report presents a brief history of the Puget Sound regulatory programs that address management of point-source discharges, disposal of dredged material, and cleanup of contami- nated sediments. The major programs discussed include: ¦ Commencement Bay Superfund investigations ¦ Puget Sound Dredged Disposal Analysis Program ¦ Washington State's Surface Water Quality Standards ¦ Washington State's Sediment Management Standards ¦ Puget Sound Estuary Program ¦ Washington State's Model Toxics Control Act. While the combined scope of these regulatory programs is far broader than that of Section 403, there are direct parallels between the types of evaluations conducted under these programs and those required under Section 403. The types of evaluations required within each program are therefore described in this report, as well as the technical approaches applied to these various types of evaluations. SEDIMENT AND WATER QUALITY ASSESSMENT TOOLS Most of the Puget Sound regulatory programs require some level of both chemical and biological assessment in determining potential impacts associated with environmental contami- nation or in monitoring permitted activities (e.g., NPDES discharges or disposal of dredged material). Various "tools" have been used in these programs to assess the chemical and ix ------- biological quality of sediment and water in Puget Sound. The sediment quality assessment tools include the triad approach, sediment quality criteria, and biological indicators (e.g., sediment toxicity tests and assessment of benthic macroinvertebrate assemblages). The water quality assessment tools include water quality criteria designed to protect aquatic life, whole-effluent toxicity testing, analysis of wastewater particulate material, and site-specific surface water cleanup levels designed to protect human health. It is expected that future development of technical guidance under the Section 403 program will require consideration of new sediment and water quality assessment tools for evaluating the impacts of discharges regulated under Section 403. It is also expected that many of the impacts on the receiving environment potentially resulting from Section 403 discharges will be the same as those already being addressed under various Puget Sound regulatory programs (e.g., sediment contamination with toxic chemicals, sediment toxicity, effects on indigenous benthic organisms, and effluent toxicity). While there are reasons why the assessment tools used in Puget Sound may not be applicable to all Section 403 discharges (e.g., the database necessary to derive empirically based sediment quality criteria may not be available in other areas of the country, or bioassay species used in Puget Sound may not be appropriate elsewhere), understanding the rationale for their application in Puget Sound may be invaluable in developing assessment tools for the Section 403 program. MODELING TECHNIQUES Applications of various modeling techniques have proven invaluable in several Puget Sound regulatory programs both for predicting future conditions under various combinations of input variables and for evaluating complex relationships among environmental variables that are not amenable to evaluation through consideration of field-collected data alone. These modeling techniques range in complexity from relatively simple models that focus on a few key processes represented by a single equation to complex computer models incorporating numerous processes. This report describes the following modeling techniques and the ways in which they have been employed in Puget Sound: ¦ Contaminant transport and fate models ¦ Human health risk assessment models ¦ Ecological risk assessment models. Ocean discharge criteria evaluations conducted for Section 403 discharges may also benefit from similar applications of modeling techniques. For example, use of contaminant transport and fate models is likely to facilitate the interpretation of the environmental impacts of these discharges. Because these models can be run with varying degrees of actual data input, they may be particularly valuable for preliminary screening-level assessments using a minimum of site-specific data. Such assessments may have direct application to determinations of no irreparable harm that must be made upon issuance or reissuance of Section 403 permits when there is insufficient site-specific information to make a determination of no unreasonable degradation. The applications of human health and ecological risk assessment models in Puget Sound regulatory programs may also serve as examples of potential uses of these models for x ------- Section 403 evaluations. Both human health and ecological risk assessments are important areas for the development of technical guidance in support of Section 403. MONITORING GUIDANCE Over the past 6 years, Puget Sound regulatory programs have expanded the attention given to monitoring of permitted wastewater discharges and other environmental monitoring programs in the area. Several important developments in these monitoring programs are therefore discussed in this report. For example, upon issuance, reissuance, or modification of NPDES permits, increased requirements are being placed on major dischargers to monitor conditions in the receiving environment to more accurately assess the effects these discharges are having on resident organisms. The Puget Sound regulatory programs have also made considerable progress in standardizing monitoring protocols to ensure the collection of high-quality monitoring data across programs. The Washington Department of Ecology, which has the delegated authority to issue wastewater discharge permits in Washington State, has also developed a manual (Ecology 1989) to assist permit writers with the development of appropriate monitoring programs for individual discharges. Together, these developments are improving the ability to detect and interpret impacts on the receiving environment, and, as a result, improving the ability to regulate pollutant releases to the environment. Just as uniform national monitoring guidance was developed under Section 301(h), the development of similar guidance may be considered for Section 403 monitoring programs. National monitoring guidance will provide consistency in developing permit requirements and identify the appropriate levels of monitoring required to support the determinations of no irreparable harm and no unreasonable degradation that must be made under Section 403. Just as there has been increased attention given in Puget Sound to monitoring of conditions in the receiving environment, there is also expected to be increased emphasis on monitoring of the receiving environment in the vicinity of Section 403 discharges. For these reasons, consi- deration of recent improvements in Puget Sound monitoring programs may be valuable in the further development of monitoring guidance under Section 403. DECISION-MAKING FRAMEWORKS Each of the major Puget Sound regulatory programs includes a framework of evaluation procedures designed to assist decision-makers with the sometimes complex process of evaluating the environmental effects of point-source discharges or in-place sediment contaminants. These decision-making frameworks use the sediment and water quality assessment tools and the modeling techniques mentioned earlier, and they also rely on the collection and analysis of monitoring data according to established protocols. These decision-making frameworks and their use of assessment tools and modeling techniques are described in this report. It is expected that future development of technical guidance under the Section 403 program will require the development of a decision-making framework for conducting the evaluations required under Section 403 in a logical, cost-effective, and nationally consistent manner. The decision-making frameworks of the Puget Sound regulatory programs are in many ways similar xi ------- to the decision-making framework that is likely to be developed for Section 403 evaluations, because many of the same or similar assessment tools and modeling techniques used in the Puget Sound programs may be used in Section 403 evaluations as well. Also, the diversity of point- source discharges covered under Section 403 makes it highly likely that a decision-making framework developed for that program will incorporate tiering of the evaluation procedures. Hence, by describing the ways in which the evaluation procedures are tiered in the Puget Sound regulatory programs, the experience gained in those programs may be applied in devising a cost- effective and efficient decision-making framework for Section 403 evaluations. APPLICABILITY OF PUGET SOUND APPROACHES TO SECTION 403 Currently, a relatively small number of ocean dischargers are likely to have sufficient site- specific information to make determinations of no unreasonable degradation (U.S. EPA 1990). Consequently, many of the Section 403 permits that will be issued over the next several years will likely be issued under the no irreparable harm provisions of Section 403. During this period, EPA will be developing further technical guidance on appropriate approaches to the determination of no unreasonable degradation. Thereafter, data collected in monitoring programs will be used to make these determinations. In the interim, however, there is a more immediate need for technical approaches that can be applied to determinations of no irreparable harm. Therefore, the final section of this report discusses the potential applicability of technical approaches currently being applied in Puget Sound to both kinds of determinations. Emphasis is placed on the common elements of these approaches in assessing impacts on the receiving environment and in managing pollutant releases to the environment. For example, there has been a common use of an effects-based approach in addressing such diverse subjects as the management of point-source discharges, the disposal of dredged material, and the cleanup of contaminated sediments. There has also been an increased focus among all of these programs on sediment contamination, stemming in large part from the realization that many of the most toxic and persistent pollutants in the marine environment have an affinity for binding to particulate matter. The following premises form the cornerstones around which the decision-making frame- works in each of the major Puget Sound regulatory programs have been developed: ¦ Decisions are generally made on the basis of a preponderance of evidence (i.e., multiple indicators such as analyses of sediment and water chemistry, water and sediment toxicity tests, and assessments of naturally occurring communities of organisms are used, and greater attention is generally focused on areas or situations when more than one indicator exhibits a significant problem). ¦ Evaluation procedures are typically tiered, with chemical criteria serving as the first tier, progressing to biological criteria in the higher tiers. Along a continuum of increasing sediment contamination, there is a common acknowledgment of two "break points." Below a threshold value, the effects of sediment contamination are considered to be insignificant; above a higher concentration threshold, the effects of sediment contamination are likely to be so severe that some form of xii ------- control or remediation will probably be required. Between these two sediment contaminant concentrations, some form of biological testing is generally required to demonstrate the presence or absence of significant effects. ¦ Some minor adverse effects on the receiving environment are considered accep- table for most activities (e.g., point-source discharges and dredged material disposal), provided such effects are reasonably limited in spatial extent, are either temporary or potentially reversible, and are of insufficient severity to be con- sidered major adverse effects. ¦ Decisions regarding either the need for restricting the release of contaminants to the environment through discharge limitations or the need for cleanup of historical contamination are made with allowance for natural recovery as one element of contaminant control. ¦ Although the decision-making frameworks provide guidance to assist decision- makers, there is always allowance for the use of best professional judgment in reaching appropriate decisions. Each of these premises is potentially applicable to the decision-making framework that will be developed for the Section 403 program. In evaluating the applicability of the technical approaches currently employed in Puget Sound to the needs of the Section 403 program, the distinction is made between the determi- nations of no irreparable harm and no unreasonable degradation. In the near future, most of the Section 403 permits will be issued or reissued on the basis of determinations of no irreparable harm. Such determinations, typically made in the absence of large amounts of site-specific information, have in the past relied heavily on the best professional judgment of the staff in the permitting agencies (i.e., EPA regional offices or delegated state agencies). However, to the extent possible, it is desirable for EPA to explore sound technical approaches that can be consistently applied throughout the country in making the determinations of no irreparable harm. Such technical approaches will, of necessity, rely on information readily available from any existing monitoring program (e.g., required effluent monitoring results), literature reviews, or short-term data collection efforts required of the dischargers (e.g., one-time monitoring of certain receiving environment conditions). Therefore, specific examples are discussed in this report of the ways in which technical approaches that have been applied in the Puget Sound regulatory programs could be adapted for such uses under Section 403. In a smaller number of cases where existing site-specific information is much more extensive, Section 403 permits will be issued or reissued following a determination of no unreasonable degradation. Many more such determinations can be expected to be made in the future as permits initially issued or reissued on the basis of determinations of no irreparable harm come up for renewal, and more extensive site-specific information will then be available from monitoring required under the permit. The complexity of these determinations is expected to be much greater than the determinations of no irreparable harm and, consequently, they will require the development of much more detailed technical guidance and decision-making xiii ------- frameworks. Therefore, specific examples are also discussed in this report of potential applications of Puget Sound technical approaches to the determinations of no unreasonable degradation that are to be made under Section 403. xiv ------- 1. INTRODUCTION 1.1 BACKGROUND Under the authority of the Clean Water Act (CWA), the U.S. Environmental Protection Agency (EPA) or delegated states issue National Pollutant Discharge Elimination System (NPDES) permits for the discharge of pollutants from point-sources into navigable waters, providing the discharge meets all applicable requirements of the law. Section 403 of the CWA identifies requirements for the permitting of point-source discharges to the territorial sea, the contiguous zone, and the oceans. Currently, federal guidelines for issuance of Section 403 permits are found in 40 CFR 125 Subpart M. The Section 403 decision-making process is illustrated in Figure 1. Issuance (or reissuance) of a Section 403 permit requires a determination of whether the discharge will cause "unreasonable degradation" of the marine environment, which is defined as any of the following: ~ Significant adverse changes in ecosystem diversity, productivity, or stability of the biological community within the area of the discharge and surrounding biological communities ~ Threat to human health through direct exposure to pollutants or through consump- tion of exposed aquatic organisms n Unreasonable loss of aesthetic, recreational, scientific, or economic values, in relation to the benefit derived from the discharge. Ten major criteria that must be considered when demonstrating no unreasonable degradation to the marine environment are listed in 40 CFR 125.122 and summarized in Table 1. If, on the basis of available information, it is determined that a discharge will cause unreasonable degradation, a discharge permit cannot be issued. If, prior to permit issuance, there is insufficient information available to make a determination of no unreasonable degradation, the discharge permit may still be issued if, among other provisions, it can be demonstrated that the discharge would not cause "irreparable harm" to the marine environment. Irreparable harm is defined as significant undesirable effects occurring after the date of permit issuance that will not be reversed after cessation or modification of the discharge. Discharge permits issued under the no irreparable harm provision of Section 403 must include monitoring requirements to collect sufficient information to determine during the next permit review cycle whether the discharge will cause unreasonable degradation. To date, the detail and thoroughness of Section 403 permit reviews have depended on the availability of resources and competing program priorities at each of the EPA Regional Offices and the delegated states (U.S. EPA 1990). EPA Headquarters is currently undertaking a number of supporting activities designed to ensure effective implementation of Section 403, including development of nationally consistent technical and procedural guidance. It is expected that the guidance being developed by EPA will integrate the evaluation criteria specific to Section 403 1 ------- Applicant submits request for issuance/reissuance of permit based on 40 CFR 125.124 Issue/reissue permit May require: - Limits - Monitoring - Special conditions Evaluation to determine unreasonable degradation based on 40 CFR 125.122 Unreasonable degradation? Information Irreparable harm? No easonable alternatives for disposal? Issue/reissue permit Must have: - Limits - Monitoring - Special conditions Yes * Permit denied / L Yes Yes Permit expiration Source: Adapted from U.S. EPA (1990) Figure 1. Section 403 decision-making process. 2 ------- TABLE 1. LIST OF OCEAN DISCHARGE CRITERIA 1. Quantities, composition, and potential for bioaccumulation or persistence of the pollutants to be discharged 2. Potential transport of such pollutants by biological, physical, or chemical pro- cesses 3. Composition and vulnerability of potentially exposed biological communities, including: Unique species or communities Endangered or threatened species Species critical to the structure or function of the ecosystem 4. Importance of the receiving water area to the surrounding biological community, for instance: Spawning sites Nursery/forage areas Migratory pathways Areas necessary for critical life stages/functions of an organism 5. Existence of special aquatic sites, including (but not limited to): Marine sanctuaries/refuges Parks National and historic monuments National seashores Wilderness areas Coral reefs 6. Potential direct and indirect impacts on human health 7. Existing or potential recreational and commercial fishing 8. Any applicable requirements of an approved Coastal Zone Management Plan (CZMP) 9. Such other factors relating to the effects of the discharge as may be appropriate 10. Marine water quality criteria Source: Adapted from 40 CFR 125.122. 3 ------- with the evolving water quality-based toxics control approach for marine waters. The Section 403 program stresses consideration of the receiving water ecosystem; protection of unique, sensitive, or ecologically critical species; and protection of human health and recreational uses. The water quality-based toxics control approach for marine waters currently focuses primarily on achieving compliance with state water quality criteria and standards by specifying allowable concentrations of pollutants within and at the edge of authorized mixing zones in the vicinity of wastewater discharges. The approach includes both chemical-specific controls (through established criteria and standards) and control of complex mixtures of chemicals and chemicals that have no applicable criteria and standards, by treating effluent toxicity as a control parameter (U.S. EPA 199Id). While the current water quality-based toxics control approach emphasizes effluent testing and compliance with water quality criteria and standards, Section 403 evaluations will also include assessment of in situ biological impacts (U.S. EPA 1990). It is expected, therefore, that the guidance developed by EPA will include monitoring requirements using such evaluation tools as sediment toxicity tests, benthic community surveys, and assessments of bioaccumulation. Hence, integration of the water quality-based toxics control approach with the Section 403 evaluation criteria should achieve a more comprehensive degree of environmental protection than could be achieved with either approach alone. 1.2 OBJECTIVE Regulatory programs currently being applied to the management of point-source discharges, the disposal of dredged material, and the cleanup of contaminated sediments in Puget Sound, Washington, have incorporated various innovative approaches to the assessment of impacts of pollutants on the receiving environment. It is expected that some of these innovative approaches may be applicable to assessments that will be conducted as part of Section 403 permit reviews. There are direct parallels between the assessments required in some of these regulatory programs and the determinations of no irreparable harm or no unreasonable degradation required under Section 403. The objective of this report is to describe the various regulatory programs currently being applied in Puget Sound, as well as the technical approaches used in those programs to assess pollutant impacts on the receiving environment. This report focuses on those assessment techniques that are potentially applicable, either directly or with minor modification, to the types of assessments required for the issuance or reissuance of Section 403 permits. Advantages and disadvantages of various options that were considered in the development of these technical approaches will also be discussed. By documenting technical approaches applied in Puget Sound regulatory programs as case studies, it is anticipated that elements of those approaches that show particular promise can be incorporated into the technical approach later proposed for implementation of Section 403. . As in other areas of the United States, historical efforts to regulate pollutant inputs to Puget Sound were primarily discharge-oriented, and, at least initially, focused on the effects of conventional pollutants (e.g., oxygen-depleting substances, suspended solids, fecal coliform bacteria, pH, and oil and grease). Prior to the 1970s, parts of Puget Sound experienced water quality problems including reduced concentrations of dissolved oxygen, fish kills, and wide- spread toxicity to oyster larvae (PSWQA 1990). During the 1970s, however, strong source control programs were implemented to reduce the amount of waste discharged from lumber and pulp mills. These controls were very effective in curbing the release of excessive amounts of 4 ------- organic matter into the water, thereby reducing problems associated with biochemical oxygen demand, and in eliminating the toxicity of the water to oyster larvae. More recently, additional requirements have been placed on municipal and industrial wastewater discharges that have further reduced the discharge of conventional pollutants to Puget Sound. There is an increasing awareness that the remaining threats to the Puget Sound ecosystem are related primarily to toxic, and not conventional, pollutants. Fortunately, Puget Sound's large volume, relatively great tidal range, and numerous large river discharges result in substantial flushing and mixing. Most areas of the sound are therefore unlikely to experience water quality problems associated with toxic pollutants because most dissolved contaminants are rapidly diluted to harmless levels. However, many toxic pollutants have an affinity for binding to particulate matter in the water column. These pollutants settle to the bottom with the particulate matter and become incorporated into the sediments. It is not surprising, therefore, that the sediments in the vicinity of various point-sources of pollutants in Puget Sound are contaminated, while much lower concentrations of toxic pollutants are found in the sediments in areas of Puget Sound far removed from point-sources. Because of this relationship between toxic pollutants and sediments, it is generally believed that many of the adverse effects associated with toxic pollutants from point-sources in Puget Sound occur as a result of sediment contamination. Consequently, the focus of most of the regulatory programs concerned with pollution in Puget Sound is now on contaminated sediments and their effects on the ecosystem (PSWQA 1990). Whereas assessment of water quality has routinely been accomplished by comparing receiving water conditions with available criteria and standards, a similar approach has not been used to assess sediment quality because of the lack of available sediment quality criteria. Consequently, a number of Puget Sound regulatory programs have used the sediment quality triad to assess sediment quality. The triad consists of three interrelated parts: 1) measurement of sediment contaminant concentrations, including both metals and organic compounds; 2) measurement of the effects (both acute and chronic) on test organisms exposed to sediments in laboratory bioassays; and 3) in situ evaluations of biological organisms. The combined assessment of these three indicators provides a more comprehensive assessment of sediment quality than could be achieved by the use of any one indicator alone. Recently, Washington became the first state to promulgate sediment quality standards that include numerical criteria for assessing sediment quality, and these standards were developed primarily using these three indicators. There will likely be a similar need for sediment quality assessment techniques as part of the technical guidance developed for Section 403. However, the needs for assessment techniques under Section 403 will not be limited to sediment quality assessment. Many of the complex issues that can be expected to be raised in the implementation of Section 403 have already been addressed in Puget Sound regulatory programs. Therefore, a broad range of assessment techniques will be addressed in this report, including methods to assess both sediment and water quality, modeling techniques, monitoring guidance, and decision-making frameworks applied in Puget Sound regulatory programs. 5 ------- 1.3 REPORT OVERVIEW Section 2 of this report presents a brief history of the Puget Sound regulatory programs that address management of point-source discharges, disposal of dredged material, and cleanup of contaminated sediment. While the combined scope of these regulatory programs is far broader than that of Section 403, there are direct parallels between the types of evaluations conducted under these programs and those required under Section 403. For example, Washington's Surface Water Quality Standards include provisions for regulating point-source discharges (e.g., establishment of water quality criteria, allowances for mixing zones, and guidance on how and where compliance with the water quality criteria will be evaluated). Also, one section of Washington's Sediment Management Standards addresses requirements for the control of point- source discharges to ensure that sediment quality and the integrity of biological communities in the vicinity of those discharges will not be compromised. In other cases, the program goals may be markedly different from the goals of Section 403 [e.g., regulation of the disposal of dredged material under the Puget Sound Dredged Disposal Analysis (PSDDA) program vs. control of point-source discharges under Section 403], although it is expected that the assessment approaches applied in the Puget Sound programs are similar to those that will be required under Section 403 (e.g., methods of assessing biological impacts of chemical contaminants or methods for assessing the likelihood of significant risks to human health). In Section 3 of this report, a detailed description is provided of the sediment and water quality assessment "tools" that have been adopted for use in Puget Sound regulatory programs. Most of these regulatory programs require some level of both chemical and biological assessment in determining potential impacts associated with environmental contamination or in monitoring permitted activities (e.g., NPDES discharges or disposal of dredged material). The sediment quality assessment tools include the triad approach, sediment quality criteria, and biological indicators (e.g., sediment toxicity tests and assessment of benthic macroinvertebrate assem- blages). The water quality assessment tools include water quality criteria designed to protect aquatic life, whole-effluent toxicity testing, analysis of wastewater particulate material, and site- specific surface water cleanup levels designed to protect human health. For each of the assessment tools discussed in this section, the rationale for its use is explained. Section 4 of this report describes several types of modeling techniques that have been applied (or are being developed for use) in the Puget Sound regulatory programs and that are potentially applicable to the types of evaluations required under Section 403. These modeling techniques include contaminant transport and fate modeling (e.g., to assess the relationship between contaminant source loading and accumulation of contaminants in the sediments, or to assess the potential for contaminated sediments to recover naturally), human health risk assessment modeling, and ecological risk assessment modeling. Each modeling approach is described in sufficient detail to allow evaluation of its potential application to the Section 403 program. The development of national monitoring guidance may be considered for Section 403 discharges. Section 5 of this report describes several related developments under the Puget Sound regulatory programs: the expanded monitoring requirements for major NPDES discharges, the development of the Puget Sound Protocols (PSEP 1990), and uniform guidance on developing monitoring requirements for discharge permits. As attention has shifted to 6 ------- assessing the effects of wastewater discharges on the receiving environment, additional monitoring requirements are being included in the permits for major Puget Sound discharges to begin to assemble a database to assess such effects. The Puget Sound Protocols (PSEP 1990) represent an attempt to achieve standardized methods across programs for collecting field samples and conducting laboratory analyses. The advantages of standardizing methods across programs will be discussed, as will the need to achieve lower than normal detection limits for certain chemical analyses to support the intended uses of the data. Guidance recently prepared by the Washington Department of Ecology (Ecology) for permit writers (Ecology 1989, 1990) provides a framework for developing permit requirements for many of the same types of monitoring that may be required for Section 403 discharges (e.g., receiving water and sediment chemistry, sediment bioassays, benthic macroinvertebrate assessments, and whole-effluent toxicity testing). Each of the major Puget Sound regulatory programs includes a framework of evaluation procedures designed to assist decision-makers with the sometimes complex process of evaluating the effects of point-source discharges or in-place sediment contaminants. Section 6 of this report outlines these decision-making frameworks and describes their use of assessment tools and modeling techniques, as appropriate. Although there are relatively minor differences among programs in the ways these elements are applied, there is a common philosophy in their basic approaches. For example, there is a common reliance on chemical sediment quality criteria as the basis for decision-making, but in each program, allowance is made for overriding the sediment quality criteria with site-specific biological tests (e.g., through the use of sediment toxicity tests or assessments of benthic macroinvertebrates). Therefore, emphasis is placed on the common elements among programs and on the underlying philosophy for the overall decision-making frameworks. A central tenet of most of the regulatory programs now being employed in Puget Sound is the concept of tiering the evaluation procedures such that not all situations are evaluated by the same rigid set of procedures. In programs as diverse as the regulation of dredged material disposal and the monitoring of NPDES discharges, tiered evaluation frameworks are employed such that situations with only a low likelihood of adverse environmental impacts are evaluated by less-costly, simplified procedures. It can be expected that similar tiering of the evaluation procedures will be valuable in the further development of Section 403 regulations and technical guidance. Hence, in Section 6 of this report, emphasis is placed on aspects of the tiered approaches currently used in Puget Sound that may be applicable to Section 403 permit decision- making. In particular, screening tools are discussed that have proven useful in deciding whether simpler or more complex evaluation procedures are appropriate. Section 7 of this report discusses the advantages and disadvantages of the various technical approaches now being employed in Puget Sound regulatory programs, and evaluates their potential applicability for addressing both the determinations of no unreasonable degradation and no irreparable harm that must be made under Section 403. For some of the 10 ocean discharge criteria employed in determining no unreasonable degradation (e.g., consideration of the potential transport and fate of pollutants or of the composition and vulnerability of exposed biological communities), assessment approaches now being employed in Puget Sound will probably be directly applicable or applicable with minor modifications. For other criteria [e.g., consideration of the requirements of a Coastal Zone Management Plan (CZMP)], 7 ------- evaluation procedures may not be amenable to the use of technical approaches recently developed in Puget Sound. Parallels between permitting under the no irreparable harm provision of Section 403 and discharge permitting in Puget Sound are also discussed. By considering what has and has not worked in Puget Sound, it should be apparent which aspects of these approaches show promise for consideration in the further development of Section 403 regulations and technical guidance. 8 ------- 2. PUGET SOUND REGULATORY PROGRAMS This section presents a brief history of the Puget Sound regulatory programs that address management of point-source discharges, disposal of dredged material, and cleanup of contami- nated sediments. While the combined scope of these regulatory programs is far broader than that of Section 403, there are direct parallels between the types of evaluations conducted under these programs and those required under Section 403. There is, for example, a common need for assessments of the effects of environmental contamination on the environment among all of these programs. The brief discussions of each program that follow therefore describe the types of evaluations required within each program, drawing parallels with those expected to be required under Section 403. The assessment approaches applied to these various types of evaluations are then described in greater detail in subsequent sections of this report. 2.1 COMMENCEMENT BAY SUPERFUND INVESTIGATIONS Commencement Bay is an urban embayment of approximately 9 mi2 in south-central Puget Sound. The bay opens to Puget Sound in the northwest, with the city of Tacoma situated on the south and southeast shores. Prior to industrialization of the area in the late 1800s, the Puyallup River delta formed the head of the bay. With development, however, extensive dredging and filling of the tideflats area occurred. Numerous industrial and commercial operations were located along the shorelines, including pulp and lumber mills, shipbuilding facilities, metal smelters, oil refineries, food processing plants, and chemical manufacturing plants. The present shoreline consists of Commencement Bay proper, eight man-made waterways, and the channelized Puyallup River. The man-made waterways of Commencement Bay now constitute one of the largest ports on the west coast. Several investigations conducted in the late 1970s and early 1980s indicated that Commence- ment Bay waterways were contaminated by a wide variety of metals (e.g., arsenic, copper, and mercury) and organic chemicals [e.g., polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAH), and chlorinated hydrocarbons]. The historical data suggested that sediment contamination was spatially extensive and highly heterogeneous. These studies also indicated areas of high sediment toxicity, accumulation of toxic substances in indigenous biota, and the presence of liver abnormalities and tumors in flatfish. As a result of these findings, Commence- ment Bay was targeted for action in 1981 under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA; commonly referred to as Superfund). At that time, Commencement Bay was the highest priority site in the state of Washington. Subsequently, in 1983, EPA reached an agreement with Ecology to conduct a remedial investigation of Commencement Bay, with Ecology delegated the lead role. The remedial investigation was completed in 1985 (Tetra Tech 1985), followed by a feasibility study in 1988 (Tetra Tech 1988a), and a record of decision (ROD) (U.S. EPA 1989a) in 1989. 9 ------- The goal of the Commencement Bay remedial investigation was to identify problem sediments and potential contaminant sources and to prioritize areas for remedial action. The goal of the Commencement Bay feasibility study was to identify and evaluate potential remedial alternatives. The ROD then selected the preferred remedial alternative for each of the eight problem areas identified in Commencement Bay. Because of the complexity of sediment contaminants and pollutant sources in Commence- ment Bay and the lack of available cleanup criteria for sediment contaminants, the remedial investigation and feasibility study (RI/FS) (Tetra Tech 1985, 1988a) required the development of a decision-making framework to assess and prioritize contaminated sediments prior to evaluating remedial alternatives. This decision-making framework incorporated a "preponder- ance-of-evidence" approach that was implemented in a stepwise manner to identify toxic problem areas. Information on the extent of sediment contamination, adverse biological effects, and potential threats to public health formed the basis for prioritization of areas for cleanup and/or source control. The decision-making framework was developed to integrate these kinds of technical information in a form that could be understood by regulatory decision-makers and the public. The framework used a series of steps to identify and rank problem areas and problem chemicals. Study areas that exhibited high values for indices of contamination and biological effects relative to Puget Sound reference areas received a high priority ranking for evaluation of pollutant sources and potential remedial action alternatives. A review of site characteristics and historical data for Commencement Bay, in conjunction with available information on the effects of contaminated sediments, led to the development of three important premises underlying the decision-making process. First, it was determined that criteria to define problem sediments could not be established a priori because of limitations in the historical database and the absence of regulatory sediment criteria at the national or state levels. Therefore, site-specific criteria were developed using data gathered as part of the remedial investigation. Second, it was determined that no single chemical or biological measure of environmental conditions could be used to define problem sediments adequately. Therefore, problem areas were defined and then ranked relative to one another based on the magnitude and extent of contamination and effects demonstrated by several independent sediment and biological indicators. Third, it was assumed that adverse biological effects were linked to environmental conditions, and that these links could be characterized empirically. Although proof of cause-and- effect relationships was not provided by these studies, quantitative relationships derived from analysis of field-collected data were used, where possible, to demonstrate links between sediment contamination and biological effects. In this sense, cause-and-effect relationships could be implied by a preponderance of field and laboratory evidence, including the correlation of specific contaminant concentrations with the occurrence of adverse biological effects. The Commencement Bay feasibility study (Tetra Tech 1988a) evaluated a wide variety of remedial alternatives for the eight problem areas. The ROD (U.S. EPA 1989a) established overall bay-wide cleanup objectives and multielement remedial strategies to be implemented independently in each of the eight problem areas. The overall remedy incorporates both source control and sediment remediation. Source control is to be achieved by imposing requirements for 1) greater degrees of wastewater treatment prior to discharge and 2) adoption of best management practices (BMPs) to reduce contaminant inputs from sources other than permitted wastewater discharges (e.g., storm water runoff, shipyards, and ore loading and unloading). 10 ------- Sediment remediation is to be achieved by a combination of natural recovery and active sediment cleanup. Areas expected to recover naturally within a 10-year period after source control measures are implemented will be monitored annually to confirm that prediction. Site-use restrictions, such as advisories against seafood consumption, will be employed to protect human health until recovery is complete. Areas not expected to recover naturally in a timely manner will be remediated when source control measures are designated acceptable by EPA and Ecology. According to the ROD (U.S. EPA 1989a), active remediation of contaminated sediments may incorporate a limited range of four confinement technologies (i.e., in-place capping, confined aquatic disposal, confined nearshore disposal, and upland disposal), each of which can provide a feasible and cost-effective means of achieving the cleanup objectives. 2.2 PUGET SOUND DREDGED DISPOSAL ANALYSIS PROGRAM Historically, open-water disposal of dredged material in Puget Sound generally occurred at sites selected by each permit applicant. Beginning in 1970, disposal site designation guidelines were formulated by an interagency committee, and through 1978, 10 public multiuser disposal sites were established for the open-water disposal of dredged material. In the early 1980s, concerns were raised by citizen groups about the continued use of some disposal sites and the quality of the dredged material being disposed of at those sites. In 1985, the U.S. Army Corps of Engineers (Corps), EPA, Ecology, and the Washington Department of Natural Resources (DNR) jointly initiated the PSDDA program. The goal of PSDDA was to develop environ- mentally safe and publicly acceptable options for unconfined, open-water disposal of dredged material. Specific PSDDA objectives were to 1) define consistent and objective evaluation procedures for evaluating the acceptability of dredged material for unconfined, open-water disposal; 2) identify acceptable public multiuser disposal sites in Puget Sound; and 3) formulate site management plans that would ensure adequate site-use controls and program accountability. The PSDDA program was a 4.5-year effort conducted in two overlapping phases, each about 3.5 years in length. Initial emphasis was placed on the development of a series of chemical and biological testing procedures to determine the suitability of sediments for disposal at open-water sites in Puget Sound. These testing procedures were then arranged in a tiered, decision-making evaluation framework to determine the acceptability of dredged material for unconfined, open-water disposal in Puget Sound (PSDDA 1988a, 1989). Initial evaluation of the sediments is based on sediment chemistry alone, using two kinds of chemical criteria: relatively low screening level concentrations for individual chemicals of concern, below which the dredged material would generally be considered acceptable for unconfined, open-water disposal, and maximum chemical concentration criteria for individual chemicals, above which the dredged material would generally be considered unacceptable for unconfined, open-water disposal. If all sediment contaminants are below the screening level concentrations, no further testing of the sediments is required, unless there is other evidence suggesting the sediments may be toxic. If, however, the concentration of one or more chemical contaminants falls between the screening level concentrations and the maximum criteria, a series of sediment toxicity tests and, potentially, a bioaccumulation test may be used to determine whether the dredged material is acceptable for unconfined, open-water disposal. If the concentration of one or more sediment contaminants exceeds the maximum criteria, the dredged material is generally considered 11 ------- unacceptable for unconfined, open-water disposal, although biological test results may still be used to override the conclusion based on sediment chemistry alone. The PSDDA evaluation procedures (PSDDA 1988a, 1989) are consistent with requirements for dredged material testing under Section 404(b)(1) of the CWA. The evaluation procedures also provide for the state water quality certification required under Section 401 of the CWA. In conjunction with developing evaluation procedures for assessing the acceptability of dredged material for unconfined, open-water disposal, the PSDDA agencies also prepared detailed guidance on the development of sampling and analysis plans for individual dredging projects (PSDDA 1988a). Recognizing the large range in scales of potential dredging projects, the sampling and analysis requirements were also tiered, such that the level of sampling required for smaller projects and for those in areas unlikely to exhibit sediment contamination was reduced in accordance with their lower likelihood of adversely affecting the environment. Included in the sampling and analysis guidance were such issues as station positioning requirements, sampling protocols, sample compositing, chemical and biological testing protocols, and test interpretation criteria. The PSDDA agencies also developed management plans (PSDDA 1988b, 1989) for disposal sites designated as part of the program. The major site management issues that were addressed included procedures for designation of disposal sites, permits and fees for site use, permit compliance inspections, environmental monitoring, data management, and implementation. 2.3 WASHINGTON STATE'S SURFACE WATER QUALITY STANDARDS In response to the Federal Water Pollution Control Act Amendments of 1972, the state of Washington first adopted water quality standards [codified as Chapter 173-201 of the Washington Administrative Code (WAC)] in 1973. These standards were designed to protect a wide range of beneficial uses for surface waters, including domestic, agricultural, and industrial water supplies; recreation; wildlife habitat; fish and shellfish; and commerce and navigation. The standards contain chemical, physical, and biological characteristics required to support beneficial uses. The standards are used to set limits on discharges to surface waters through Ecology's water quality permitting program. They also guide Ecology's water quality activities in other areas where discharge permits are not required. Just as in the water quality standards of other states, Washington's Surface Water Quality Standards (Chapter 173-201 WAC) define general water use and criteria classes for the various surface water bodies of the state. For each class, the standards define characteristic uses that are to be protected and specific criteria for conventional water quality variables (e.g., fecal coliform bacteria, dissolved oxygen, total dissolved gas, temperature, pH, and turbidity). The Surface Water Quality Standards specifically assign many of the surface water bodies of the state to one of these classes; those that are not specifically assigned are classified according to general guidelines. In recent years, there have been substantial changes made to the Surface Water Quality Standards that have improved the ability to control water pollution through wastewater discharge 12 ------- permits. Prior to 1988, toxic substances were only addressed in the standards by a narrative statement that they were not to be discharged to surface waters at concentrations that would adversely affect characteristic water uses, cause acute or chronic effects to aquatic biota, or adversely affect public health. In response to the federal Water Quality Act of 1987, EPA's numerical water quality criteria for a number of toxic substances were adopted in 1988 as standards within Washington's Surface Water Quality Standards (Chapter 173-201 WAC). In 1991, the Surface Water Quality Standards are undergoing their triennial review, and additional numerical water quality criteria are proposed for incorporation as standards (Ecology 1991). Prior to 1991, the Surface Water Quality Standards included provision for mixing (or dilution) zones adjacent to or surrounding wastewater discharges. Within these mixing zones, exceedances of the water quality criteria were allowed. Although there were official guidelines describing specifications for mixing zone dimensions, these were not incorporated as part of the standards. There was also no guidance provided on where the acute and chronic criteria should be applied. In 1991, the proposed revisions to the Surface Water Quality Standards (Ecology 1991) include specifications for maximum mixing zone dimensions in various water bodies and specific requirements for the point of compliance with acute and chronic criteria. Chronic criteria must be complied with at the boundary of the mixing zone; acute criteria must be complied with at a point within the mixing zone defined in accordance with guidelines in EPA's Technical Support Document for Water Quality-Based Toxics Control (U.S. EPA 1991d). Prior to 1991, the Surface Water Quality Standards did not include specific provisions for the direct assessment of wastewater toxicity. The proposed revisions to the standards (Ecology 1991) include provisions for the use of acute and chronic toxicity testing, and biological assessments, as appropriate, to assess wastewater toxicity. Ecology has also developed Biomonitoring Guidance for Department of Ecology Permit Writers (Ecology 1990) that describes the use of approved acute and chronic toxicity testing procedures in assessing wastewater toxicity to both marine and freshwater species. 2.4 WASHINGTON STATE'S SEDIMENT MANAGEMENT STANDARDS It has been recognized since at least the early 1980s that there are areas of Puget Sound, especially in urban embayments, where sediments are contaminated with various chemical pollutants (Malins et al. 1980; Dexter et al. 1981; Riley et al. 1981; Long 1982). Sediment contamination in those areas has been associated with impacts on animals living in the sediment and with the development of tumors and other abnormalities in bottom-feeding fish (Malins et al. 1984; Becker et al. 1987). In addition, fish, crabs, and clams from these areas have been found to bioaccumulate pollutants which, in turn, pose a risk to human health (Landolt et al. 1985; Tetra Tech 1988b). Contamination in sediments originates from numerous sources, including both historical practices and ongoing point and nonpoint discharges. Historically, laws that regulated discharges to surface waters of the state were concerned primarily with water quality, rather than sediment quality, and therefore they did not directly address the problems associated with sediment contamination. Because toxic pollutants from the water column can accumulate in the sediments, harmful levels of sediment contamination can occur even when the water column is not seriously 13 ------- contaminated. However, the absence of any adopted sediment quality standards made it difficult to achieve consistent protection of sediment quality. Existing programs governing the regulation of point and nonpoint discharges; the management of dredging and disposal of dredged material; and the identification, ranking, and cleanup of contaminated sediment sites were hampered by the lack of coordinated goals and policies addressing the prevention of sediment contamination. Regulation of sources of toxic pollutants through existing permit programs generally addressed the quantity, but not the quality, of suspended particles in effluents that could ultimately affect the quality of the sediments. State and federal water quality, hazardous waste, and cleanup laws were often in disagreement concerning the need for the protection of sediments, the level of protection necessary, and the appropriate scientific methods for measuring the chemical and biological quality of sediments. Developed as one of the requirements of the Puget Sound Estuary Program (PSEP) (see Section 2.5), the Puget Sound Water Quality Management Plan [originally adopted in 1987 and, after several iterations, formally recognized as the Comprehensive Conservation and Manage- ment Plan (CCMP) for Puget Sound (PSWQA 1990)] required a unified approach to the management of contaminated sediments and the regulation of dredging, dredged material disposal, and municipal and industrial discharges. Among other directives, the Plan required Ecology to develop Puget Sound sediment quality standards; sediment source control standards, including provisions for sediment impact zones (equivalent to mixing zones in the water column, within which water quality standards may be exceeded); and contaminated sediment cleanup standards. Over the last 4 years, Ecology developed these standards, with substantial inputs from scientific experts, staff from various state and federal agencies, the regulated community, and the public. This process culminated in March 1991 with the promulgation of the Washington State Sediment Management Standards (codified as Chapter 173-204 WAC). The Sediment Management Standards address three main issues: ¦ First, the Sediment Management Standards identify a long-term goal for the quality of sediment in Puget Sound, embodied in definitive sediment quality standards. Standards for other areas of the state are reserved for future develop- ment. The long-term goal is that sediment contamination should be below levels that would have acute or chronic adverse effects on biological resources or pose a significant risk to human health. Quantitative chemical contaminant levels are stipulated as the sediment quality standards for 47 contaminants or groups of contaminants of concern in Puget Sound. In addition, the standards establish procedures for evaluating biological effects through the conduct of acute and chronic biological tests, including sediment toxicity tests and the assessment of indigenous communities of benthic macroinvertebrates. ¦ Second, the Sediment Management Standards establish sediment source control standards for managing sediment contamination that results from ongoing wastewater discharges. In recognition of the fact that some current and future discharges may not be able to meet the long-term sediment quality goal, provision is made for establishment of an area in the immediate vicinity of a discharge (i.e., a sediment impact zone) within which exceedances of the sediment quality 14 ------- standards are allowed. However, the sediment source control standards establish maximum levels of chemical contamination and biological effects that will be allowed even within such sediment impact zones. ¦ Third, the Sediment Management Standards establish sediment cleanup standards, including a decision process for identifying contaminated sediment areas and determining appropriate cleanup responses. The cleanup decision process includes screening procedures designed to focus limited resources on areas of sufficient concern to warrant consideration of active cleanup. In some cases, it is recog- nized that the environmental disruption resulting from contaminated sediment removal actions or the cost of cleanup may outweigh the adverse environmental effects of leaving the sediments in place. For these reasons, the cleanup standards allow for a case-by-case consideration of technical limitations and cost in setting the standard for the quality of sediments left in place after cleanup. The cleanup standards also allow for natural recovery (e.g., through burial of contaminated sediments by natural deposition of clean sediments, mixing of cleaner surface sediments with contaminated deeper sediments, biodegradation, or diffusion into the overlying water) as one element of sediment remediation, provided natural recovery will achieve sufficient reduction in sediment contamination within a reasonable time frame. 2.5 PUGET SOUND ESTUARY PROGRAM Prior to formal establishment of a national program targeting contaminant problems in estuaries nationwide, the Washington state legislature created the Puget Sound Water Quality Authority (PSWQA) in 1985 to develop a regional management plan for Puget Sound. Initially, EPA provided funds to conduct studies and characterize contaminant problems in Puget Sound. Under the 1987 amendments to the CWA, Congress formally established the National Estuary Program. Under Section 320 of the CWA, Puget Sound was designated by EPA as an estuary of national significance in 1988. One requirement of the National Estuary Program is that a CCMP must be developed for each estuary of national significance. PSEP was established to ensure proper problem identification, planning, and program implementation, and is comanaged by EPA Region 10, PSWQA, and Ecology. Under the management structure of PSEP, EPA is responsible for problem identification and characterization, PSWQA is responsible for developing the Puget Sound Water Quality Management Plan (which serves as the CCMP for the Puget Sound region) and overseeing plan implementation, and Ecology is responsible for implementing plan programs and developing necessary criteria to implement programs. In addition to these three agencies, the management structure of PSEP includes a Management Committee, which is responsible for overall coordination of Puget Sound programs and for assisting in program implementation, and a Technical Advisory Committee, responsible for providing technical review and guidance. Although PSEP activities are directed toward a variety of water quality issues in Puget Sound, a substantial part of the effort has been associated with the assessment and management of point-source pollution and contaminated sediments. One of the major activities of PSEP is the Urban Bay Action Program, which is conducted jointly by EPA and Ecology with other state 15 ------- and local agencies. The Urban Bay Action Program provides a coordinated mechanism for conducting the following activities in a target embayment: 1) data compilation and identification of problem areas; 2) identification of agency activities and management gaps and development of a source control action plan; and 3) implementation of remedial actions such as source control and sediment cleanup (PTI 1990). From 1985 to 1991, action plans were either completed or are in the final phases of completion for seven urban embayments in Puget Sound. In addition to assessing contaminated areas of Puget Sound, PSEP has played a central role in the development of standardized protocols for conducting field and laboratory assessments in Puget Sound. The use of standardized protocols allows for easy comparison of environmental data with regulatory standards and reference conditions, allows for comparison of data from different studies, and enhances development of a comprehensive management strategy. The Puget Sound Protocols (PSEP 1990) were developed using a consensus-building approach in a workshop format with participation by regional scientists from state and federal agencies, consulting firms, analytical laboratories, and academic institutions. The protocols are produced in a loose-leaf format and are revised periodically to incorporate new information. The 1991 Puget Sound Water Quality Management Plan (PSWQA 1990) was recognized by EPA in May 1991 as the nation's first CCMP under the National Estuary Program. The Plan contains numerous programs that address the management and characterization of contaminated areas of Puget Sound and control of point-source pollution. The Plan also serves as the impetus for development of the contaminated sediment cleanup process in Washington State. Three major programs in the Puget Sound Water Quality Management Plan address point-source pollution and environmental assessment. The first program, the Municipal and Industrial Discharges Program, includes 28 elements to control point-source discharges and evaluate their impacts. Program elements include requirements for adopting EPA water quality criteria, developing standards to classify sediments having adverse effects, developing criteria for water column mixing zones and sediment impact zones, incorporating toxicant effluent limits into permits, and including toxicity testing and benthic macroinvertebrate monitoring requirements in permits. The second program, the Contaminated Sediments and Dredging Program, focuses on the processes for contaminated sediment cleanup and disposal. Elements of this program include 1) a program and standards for unconfined, open-water disposal of sediments (i.e., PSDDA); 2) confined sediment disposal standards; and 3) contaminated sediment investigations and guidelines, which have since been embodied in the Sediment Management Standards. The third program, the Puget Sound Ambient Monitoring Program (PSAMP), requires periodic monitoring of sediment, marine water, fresh water, shellfish, fish, birds, marine mam- mals, and nearshore habitat throughout Puget Sound (Copping et al. 1990). Monitoring stations are generally located away from urbanized areas, so that an indication of general environmental quality, rather than environmental quality associated with specific contaminant sources, can be determined. 16 ------- 2.6 WASHINGTON STATE'S MODEL TOXICS CONTROL ACT Washington State's Model Toxics Control Act (MTCA) was passed as a citizen's initiative in November 1988. MTCA is the state equivalent of the federal CERCLA legislation and provides an independent authority, outside of CERCLA, for the state to require and enforce cleanup actions at hazardous waste sites. The purpose of MTCA, as stated in the act, is to "raise sufficient funds to clean up all hazardous waste sites and to prevent the creation of future hazards due to improper disposal of toxic waste into the state's land and waters." MTCA addresses both the release of hazardous substances caused by past practices as well as ongoing or potential releases of hazardous substances caused by current practices. Ecology is responsible for implementation and enforcement of MTCA. Since passage of MTCA, Ecology has developed the MTCA Cleanup Regulation (Chapter 173-340 WAC), which provides the framework for implementation of the act. The MTCA Cleanup Regulation defines the administrative processes for identifying, investigating, and cleaning up hazardous waste sites and sites with leaking underground storage tanks. The primary focus of the MTCA Cleanup Regulation is on cleanup of terrestrial resources contami- nated by hazardous substances, but the regulations also provide guidance for cleanup of aquatic resources. Unlike many similar types of both state and federal legislation, the MTCA Cleanup Regulation specifically addresses the derivation of site-specific cleanup levels for the following media: groundwater, surface water, soil, and air. The regulations include specific statistical methods and mathematical models to derive site-specific cleanup levels for these media. However, the MTCA Cleanup Regulation does not address derivation of site-specific cleanup levels for aquatic sediments; instead, the sediment cleanup standards section of the Sediment Management Standards (see Section 2.4) is included in the MTCA Cleanup Regulation by reference. The Surface Water Quality Standards (see Section 2.3) and EPA ambient water quality criteria (U.S. EPA 1986) are also applicable under MTCA. The derivation of surface water cleanup levels under MTCA is based on human health risk assessment methods using ingestion of seafood as the primary exposure route. An approach to deriving site-specific surface water cleanup levels that are explicitly protective of ecological receptors (PTI, in preparation) is currently undergoing review by Ecology's Ecological Advisory Subcommittee. The approach is a tiered hazard assessment that combines chemical water quality criteria derived by U.S. EPA (1986), results of toxicity tests conducted on laboratory-raised organisms using site water, and analysis of indigenous aquatic communities. The cleanup levels selected under MTCA will be the most stringent of the criteria either available in applicable state and federal laws or developed as site-specific cleanup standards under MTCA. However, if the natural background concentration is higher than the selected cleanup level, the natural background concentration will be selected as the cleanup level. 17 ------- 3. SEDIMENT AND WATER QUALITY ASSESSMENT TOOLS Most of the Puget Sound regulatory programs require some level of both chemical and biological assessment in determining potential impacts associated with environmental contami- nation or in monitoring permitted activities (e.g., NPDES discharges or disposal of dredged material). This section describes various tools that have been used in these Puget Sound regulatory programs to assess the chemical and biological quality of sediment and water in Puget Sound. For each assessment tool discussed in this section, the rationale for its use will be explained. It is expected that future development of technical guidance under the Section 403 program will require consideration of new sediment and water quality assessment tools for evaluating the impacts of discharges regulated under Section 403. It is also expected that many of the impacts on the receiving environment potentially resulting from Section 403 discharges will be the same as those already being addressed under various Puget Sound regulatory programs (e.g., sediment contamination with toxic chemicals, sediment toxicity, effects on indigenous benthic organisms, and effluent toxicity). While there are reasons why the assessment tools used in Puget Sound may not be applicable to all Section 403 discharges (e.g., the database necessary to derive empirically based sediment quality criteria may not be available in other areas of the country, or bioassay species used in Puget Sound may not be appropriate elsewhere), understanding the rationale for their application in Puget Sound may be invaluable in developing assessment tools for the Section 403 program. 3.1 SEDIMENT QUALITY ASSESSMENT TOOLS Several Puget Sound regulatory programs have adopted an approach for assessing sediment quality that uses synoptically collected biological and chemical information. The approach, termed the triad approach, is described by Chapman (1986). The triad approach uses three kinds of indicators to assess sediment toxicity: bulk sediment chemistry concentrations, sediment toxicity tests, and in situ evaluations of biological organisms. In Puget Sound, five sediment toxicity tests and in situ evaluations of benthic macroinvertebrate assemblages have been the primary biological indicators used to assess sediment quality. Each of these biological indicators is described in detail in Section 3.1.2. However, before the indicators are described, Section 3.1.1 discusses how the triad approach has been used to assess sediment quality in Puget Sound. 3.1.1 Sediment Quality Assessment The triad approach has been used extensively in Puget Sound for the assessment of sediment toxicity because it provides a more integrated assessment of sediment quality than do approaches 18 ------- based on single environmental indicators (Long and Chapman 1986; Becker et al. 1989). Because there are advantages and disadvantages to using each kind of environmental indicator, the triad approach is useful for combining the advantages of multiple indicators, thereby providing an environmentally protective assessment of sediment quality. Sediment chemical concentrations are used to identify the key chemicals that may be responsible for any observed biological effects and to assist in the identification of potential sources of contamination. However, these concentrations do not conclusively indicate whether adverse biological effects are present. The biological indicators provide empirical evidence of the effects of chemical toxicity and thereby avoid the uncertainties associated with predicting effects based on chemical concentrations alone. The triad approach is therefore an effects-based approach. Sediment toxicity tests are conducted in the laboratory on field-collected sediments and allow toxicity to be assessed under carefully controlled and standardized conditions. However, uncertainties are encountered when these results are extrapolated to more complex field situations. Although in situ evaluations of benthic macroinvertebrate assemblages allow the direct assessment of biological effects in a field setting, many environmental variables are not controlled during these evaluations, which adds uncertainty to the relationship between any observed effects and chemical toxicity. The triad approach was first applied in Puget Sound as part of the Commencement Bay remedial investigation (Tetra Tech 1985). The full triad of environmental indicators was evaluated at approximately 50 stations, and sediment chemistry alone was evaluated at approximately 50 additional stations. To relate biological effects to the sediment chemical concentrations measured at the latter 50 stations, an empirical approach, called the Apparent Effects Threshold (AET) approach, was developed using data from the 50 stations at which the full triad of indicators was measured. Briefly, an AET is the chemical-specific concentration above which statistically significant biological effects were always observed in the Commence- ment Bay database used to generate the AET (Barrick et al. 1989). During the Commencement Bay remedial investigation, AET values were developed for individual chemicals or chemical groups (e.g., PCBs) for three sediment toxicity tests (i.e., amphipod mortality, oyster larvae abnormality, and Microtox® bioluminescence) and for in situ evaluations of benthic macroinver- tebrate assemblages (see Section 3.1.2). These AET values were then used to assess the potential for adverse biological effects at stations where only chemical measurements were available. Various other kinds of field, laboratory, and theoretical approaches for developing sediment quality values were evaluated by the federal and state regulatory agencies, but none were considered as useful as the AET approach in meeting the objectives (Becker et al. 1989). Following the use of the AET approach in the Commencement Bay remedial investigation, the AET database was expanded to include the results from other Puget Sound studies in which synoptically collected chemical and biological data were available, and the AET values were updated based on this new information (Barrick et al. 1988). The AET approach has been adopted by a number of Puget Sound regulatory programs to develop sediment quality values for Puget Sound because 1) it is an effects-based approach, 2) it has demonstrated relatively high reliability in classifying Puget Sound sediment samples as impacted or not impacted, and 3) it can be used to develop sediment quality values for the greatest number and widest range of chemicals of concern in the sound (Becker et al. 1989). Puget Sound sediment quality values generated using the AET approach are currently available for approximately 50 chemicals or 19 ------- chemical groups (Barrick et al. 1988). The number varies slightly for the different regulatory programs in which these sediment quality values are used. These chemicals are the ones for which a sufficient amount of information is available to generate AET values. Most of these chemicals have been selected for evaluation in past studies because they are EPA priority pollutants and because they are expected to be found throughout many of the urbanized areas of Puget Sound. Although this group of chemicals does not include all of the contaminants that may be present in Puget Sound sediments, it includes representatives of most major groups of contaminants and therefore these contaminants are probably indicative of most kinds of contamination in Puget Sound (assuming that many of the unmeasured contaminants covary with the measured contaminants). However, sediment quality values do not exist for some important chemicals (such as tributyltin, a constituent of some antifouling boat paints, and chlorinated guaiacols, which are contaminants from pulp mills) that may not covary with other chemicals because they are specific to particular industries or localized uses and therefore are not widespread in Puget Sound sediments. As additional information is collected in future studies, sediment quality values may be developed for many of these chemicals. The reliability of the Puget Sound AET values has been evaluated by estimating their sensitivity (i.e., proportion of impacted stations that were correctly predicted) and efficiency (i.e., proportion of stations designated as impacted that were correctly predicted) (Barrick and Beller 1989). Sensitivity ranged from 58 to 93 percent, and efficiency ranged from 37 to 72 percent, depending on the biological indicator. Overall reliability (i.e., percentage of all predictions that are correct) was highest for the Microtox® and oyster larvae AET values. Both the oyster larvae and Microtox® bioassays rely primarily on exposure to contaminants released from the sediments into the water and do not represent direct sediment exposures (e.g., contact or ingestion). Nevertheless, these toxicity test responses display a high concordance with alterations in benthic macroinvertebrate percentages (81 percent concordance for oyster larvae; 68 percent concordance for Microtox®; P<0.01) (Becker et al. 1990). The EPA Office of Water Criteria and Standards is investigating the use of equilibrium partitioning (EP) theory to develop national sediment quality criteria (U.S. EPA 1988a). A theoretical model is used to describe the EP of nonpolar organic chemicals between sediment organic matter and interstitial water. The model is used to calculate the interstitial water concentration of a contaminant associated with a given bulk sediment concentration of that contaminant. The interstitial water concentration of that contaminant is then compared with the corresponding EPA ambient water quality criterion (U.S. EPA 1986). In an evaluation of the reliability of AET and EP sediment quality values, the sensitivity and efficiency of the EP sediment quality values to predicting biological effects in Puget Sound (as indicated by sediment toxicity tests and infaunal abundances) were generally less than the sensitivity and efficiency of the corresponding AET values (Barrick and Beller 1989). Several Puget Sound regulatory programs have used the triad and AET approaches in combination to assess or regulate sediment contamination in Puget Sound. The general approaches used by the different programs are similar. Sediment quality values derived using the AET approach serve as screening tools for sediments in which concentrations of individual chemicals are either very low (e.g., below the lowest AET values for all chemicals, and therefore biological effects would rarely be expected) or very high (e.g., above the AET values for multiple biological indicators, and therefore biological effects would almost always be 20 ------- expected). In support of the AET-derived sediment quality values, the triad approach (i.e., the synoptic evaluation of chemical contamination and biological effects) is used to assess the toxicity of sediments in which chemical concentrations fall between the lower and upper screening levels. This combination of approaches is considered both cost-effective and environmentally protective because 1) it does not require that biological testing be conducted for all sediments and 2) it focuses biological testing on those sediments for which predictions of effects based on chemical concentrations alone have the highest degree of uncertainty. To be additionally protective, the regulatory programs reserve the right to require biological testing for any sediment when there is a reason to believe that the sediment may be toxic, regardless of whether the measured chemical concentrations exceed the lower screening levels established by the AET approach. This right was reserved because most chemical evaluations do not include all potential contaminants that may be present at a site, and because sediment quality values do not account for all potential interactive effects (additive or synergistic) that may increase toxicity beyond that expected on the basis of the concentrations of individual chemicals. The evaluations of biological indicators for both the triad and AET approaches are based on statistical comparisons with reference conditions to ensure that adverse effects are identified using objective criteria at known levels of uncertainty. Depending on the biological indicator, statistical evaluations are typically conducted using analysis of variance (ANOVA), analysis of covariance (ANCOVA), or f-tests at an alpha level of 0.05. The biological responses at potentially contaminated stations are compared statistically with the responses observed at reference stations within Puget Sound. The reference stations are located in areas where chemical contamination has been documented to be minimal. Reference conditions are selected to represent the conditions expected to be found in a contaminated area if the sediment contami- nation had not occurred. Ecology is currently developing performance standards for Puget Sound reference areas to guide the selection of reference stations in future studies (Pastorok et al. 1989). 3.1.2 Biological Indicators As mentioned in the previous section, the biological indicators used by Puget Sound regulatory programs include sediment toxicity tests and in situ evaluations of benthic macroinver- tebrate assemblages. Each of these indicators is described below. Sediment Toxicity Tests—Puget Sound regulatory programs have relied primarily on the following five sediment toxicity tests to evaluate sediment quality in Puget Sound: ¦ Amphipod mortality test ¦ Juvenile polychaete (Neanthes) mortality test ¦ Bivalve larvae abnormality test ¦ Echinoderm embryo abnormality test ¦ Microtox® bioluminescence test. 21 ------- These tests were selected because standardized protocols were available and because they represent a broad range of the kinds of biological effects that may be associated with sediment contamination in Puget Sound. The tests include representatives of diverse biological groups, including bacteria and four phyla of higher animals (i.e., Annelida, Mollusca, Arthropoda, and Echinodermata). Life stages include embryonic, juvenile, and adult organisms. Bioassay endpoints include lethality and various sublethal endpoints (i.e., growth reduction, abnormal development, and metabolic alteration). Test durations range from 15 minutes to 20 days. The key elements of each of the five sediment toxicity tests are as follows: ¦ Amphipod mortality test—This test measures mortality of adult amphipods exposed for 10 days to test sediment. The test species used in Puget Sound is Rhepoxynius abronius. Protocols are described by Swartz et al. (1985), ASTM (1990), and PSEP (1991). Adult amphipods are collected in the field and acclimated to the test temperature and salinity prior to testing. For each bioassay replicate, 20 amphipods are exposed to a 2-cm layer of bedded test sediment in a 1-liter chamber filled with clean seawater. Five replicate analyses are conducted for each sample. After the 10-day exposure period, the surviving amphipods in each test chamber are sieved from the sediment and counted. Percent mortality is determined relative to the total of 20 individuals added to each chamber at the beginning of the test. Quality assurance and quality control (QA/QC) procedures include the use of positive and negative controls and monitoring of water quality in the test chambers. Mean mortality of amphipods in the negative controls must not exceed 10 percent, or the test results are not considered valid. ¦ Juvenile polychaete mortality test—This test measures mortality and growth in juvenile polychaetes exposed for 20 days to test sediment. The test species used in Puget Sound is Neanthes sp. Protocols are described by Johns et al. (1990) and PSEP (1991). Juvenile polychaetes are obtained from laboratory cultures and acclimated to the test temperature and salinity prior to testing. For each bioassay replicate, five polychaetes of relatively uniform size are exposed to 150 grams of test sediment in a 1-liter chamber filled with clean seawater. Five replicate chambers are used for each sample. Because the polychaetes are fed during the exposure period, 33 percent of the water volume in each chamber is exchanged every third day to prevent water quality from deteriorating. After the 20-day exposure period, the survivors in each test chamber are counted. Percent mortality is determined relative to the total of five individuals added to each chamber at the start of the test. All survivors are dried and weighed to determine final biomass for each replicate. QA/QC procedures include the use of positive and negative controls and water quality monitoring. ¦ Bivalve larvae abnormality test—This test measures mortality and developmental abnormalities in bivalve mollusc larvae exposed for 48 hours to test sediment. The test species used in Puget Sound include the edible mussel, Mytilus edulis, and the Pacific oyster, Crassostrea gigas. Protocols are described by Chapman and Morgan (1983) and PSEP (1991) and are based largely on the methods described for water by ASTM (1985). Adult organisms are collected in the field and spawned in the laboratory after appropriate conditioning. For each bioassay 22 ------- replicate, 20,000-40,000 developing embryos are added to a 1-liter test chamber within 2 hours of fertilization. Each test chamber contains 20 grams of bedded test sediment and is filled with clean seawater. Five replicate analyses are conducted for each sample. After the 48-hour exposure period, all normal and abnormal larvae in a 10-mL subsample of the overlying water are counted using a microscope. An abnormal larva is defined as one that fails to transform into the fully shelled, hinged, D-shaped prodissoconch I stage. Mean mortality is determined relative to the number of larvae that survive a 48-hour exposure to clean seawater. Mean abnormality is determined relative to the total number of larvae evaluated microscopically. QA/QC procedures include the use of positive and negative controls and water quality monitoring. Mean mortality and abnor- mality of embryos in the negative controls must not be greater than 30 and 10 percent, respectively, or the test results are not considered valid. ¦ Echinoderm embryo abnormality test—This test measures mortality and develop- mental abnormalities in echinoderm embryos exposed for 48 hours to test sediment. The test species used in Puget Sound include the sand dollar, Dendras- ter excentricus; the purple sea urchin, Strongylocentrotus purpuratus; and the green sea urchin, S. droebachiensis. Protocols are described by Dinnel and Stober (1985) and PSEP (1991). Adult echinoderms are collected in the field and spawned in the laboratory. The remainder of this test is similar to the bivalve larvae abnormality test, except that approximately 12,000 embryos are added to each 1-liter test chamber, and abnormal embryos are defined as those that fail to develop into normal pluteus larvae. ¦ Microtox® bioluminescence test—This test measures the reduction in luminescence for bacteria exposed for 15 minutes to a saline extract of test sediment. The test species used in Puget Sound is the bioluminescent bacterium Photobacterium phosphoreum. Protocols are described by Beckman Instruments (1982), Williams et al. (1986), and PSEP (1991). Bacteria are obtained in a freeze-dried form and are rehydrated in the laboratory within 5 hours of testing. For each bioassay replicate, an aliquot of sediment extract and Microtox® diluent is placed in a cuvette and transferred to an automated toxicity analyzer system. A series of four extract dilutions and one diluent blank are evaluated for each sample. Duplicate subsamples of each final extract dilution are analyzed. Bioluminescence is measured initially and after the 15-minute exposure period, and the decrease in luminescence is determined by subtraction (with correction for blanks). QA/QC procedures include the use of positive and negative controls. Chapman et al. (1985) and Long (unpublished) summarized results of various bioassays used in Puget Sound. Most investigators (e.g., Chapman et al. 1985; Long, unpublished; Pastorok and Becker 1990) suggest that a tiered battery of bioassays is optimal for predicting biological effects in the field. Williams et al. (1986) demonstrated a significant overall concordance (Kendall's coefficient=0.64; P<0.001) among the results of the oyster larvae (Crassostrea gigas) abnormality, amphipod (Rhepoxynius abronius) mortality, and Microtox® (Photobacterium phosphoreum) bioassays. However, Williams et al. (1986) noted that substantial variations between paired combinations of these bioassays may be attributable to differential sensitivity to 23 ------- individual contaminants, differences in exposure routes, and the heterogeneous distribution of contaminants in sediments. Pastorok and Becker (1990) compared 13 endpoints from 7 sediment bioassays that have been used in Puget Sound and ranked their statistical sensitivity in terms of frequency of detecting significantly increased toxicity (P< 0.05) relative to reference conditions. The Microtox® (Photobacterium phosphoreum) organic extract test and the echinoderm (Dendraster excentricus) embryo test were the most sensitive bioassays based on the number of significant (P<0.05) effects detected relative to reference area sediments. The order of sensitivity of the other tests (from highest to lowest) was as follows: Microtox® (Photobacterium phosphoreum) saline extract > amphipod (Rhepoxynius abronius) mortality > polychaete (Neanthes sp.) biomass > polychaete mortality > Rhepoxynius nonreburial > amphipod (Eohaustorius estuarius) nonreburial = geoduck (Panopa generosa) mortality = echinoderm (Dendraster excentricus) chromosomal abnormality. When all bioassay endpoints were compared using the magnitude of response, a relatively low concordance was observed among the various tests. Lack of overall concordance among bioassays with diverse endpoints most likely resulted from differential sensitivity to different kinds of chemicals among bioassays related to the specific endpoint, the test species, the life stage (i.e., embryo, juvenile, or adult), or the duration of exposure (i.e., 15 minutes to 20 days). The lack of overall concordance among a wide range of end points supports an approach based on a battery of bioassays to test sediment toxicity. Evaluations of Benthic Macroinvertebrate Assemblages—As mentioned previously, most evaluations of the in situ effects of chemical toxicity in Puget Sound have addressed effects on benthic macroinvertebrate assemblages. Benthic macroinvertebrates are defined as those invertebrates retained on a sieve having a mesh size of 1.0 mm. These organisms are considered appropriate indicators of site-specific sediment toxicity because they are relatively stationary and live in close contact with bottom sediments. These organisms are particularly important in marine ecosystems because they are a major food source for higher organisms such as fishes. Because benthic macroinvertebrate assemblages are continuously exposed to sediment contami- nants, they provide an estimate of the combined effects of both short-term (e.g., days) and long- term (e.g., months) exposure to toxic chemicals. While a wide variety of sampling devices can be used to collect sediment samples for the analysis of benthic macroinvertebrate assemblages, the most common sampling device employed in Puget Sound investigations has been the 0.1 -m2 van Veen grab sampler. Replicate samples must be collected for statistical comparisons of assemblages among sampling locations; the recommended number of replicate samples is five per station. Sampling and analysis protocols for assessment of benthic macroinvertebrate assemblages are described by PSEP (1987). The major characteristics evaluated for benthic macroinvertebrate assemblages as part of Puget Sound regulatory programs are abundances of three major taxa: Polychaeta, Mollusca, and Crustacea. As a group, these three taxa generally comprise over 90 percent of the individuals found in benthic assemblages in Puget Sound. Abundance was selected as the primary indicator of effects on benthic assemblages because it is an objective measurement that can be quantified adequately in field-collected samples (Becker et al. 1989). Abundances of major taxa were selected instead of species abundances because reductions in the abundances of 24 ------- major taxa are presumed to be more environmentally significant than reductions in the abundances of individual species. In addition, reductions in the abundances of major taxa can often be attributed to chemical toxicity more readily than can more subtle shifts in species abundances, which may be due to factors other than toxicity (e.g., temperature, salinity, and sediment grain-size distribution). Based on the data collected as part of the Commencement Bay remedial investigation, the concordance between impact designations based on reductions in the abundances of major benthic taxa and designations based on classification analyses of species abundances was relatively high (76 percent) and significant (P<0.01). This result suggests that patterns based on abundances of major taxa are largely representative of patterns based on species abundances. Surveys of benthic macroinvertebrate assemblages that estimate the magnitude of depres- sions in major taxa abundances have proven useful in ranking contaminated sediment problem areas in Puget Sound (Barrick et al. 1989; Becker et al. 1990). Compared with laboratory toxicity bioassays, the relevance of surveys of indigenous populations is often more obvious to regulators and to the public. However, in interpreting such results, caution is needed to avoid the potential confounding effects of natural factors that may obscure potential effects of contami- nants or lead to erroneous identification of contaminant effects. For example, comparisons of benthic taxa abundances between potentially contaminated sites and reference areas should be stratified by season and by habitat features (e.g., sediment grain size and total organic carbon content). 3.2 WATER QUALITY ASSESSMENT TOOLS As noted in Section 1, historical efforts to regulate pollutant inputs to Puget Sound were directed primarily at controlling conventional pollutants. These efforts have proven successful, and water quality problems related to these pollutants are now relatively rare in the Puget Sound region. However, as the focus of pollution control efforts shifted to toxic pollutants, it became increasingly apparent that additional tools were needed to assess the effects of toxic pollutants on the receiving environment. Prompted in part by the directives of the 1991 Puget Sound Water Quality Management Plan (PSWQA 1990), Ecology recently adopted the following tools to assess the effects of toxic pollutants within the water column: 1) water quality criteria for toxic pollutants; 2) whole-effluent toxicity testing to assess the acute and chronic effects of wastewater discharges; and 3) monitoring of wastewater particulate material. In addition to the directives of the 1991 Puget Sound Water Quality Management Plan (PSWQA 1990), MTCA required development of a method to establish site-specific, surface water cleanup criteria based on the human health risks of consuming contaminated fish and shellfish. Sections 3.2.1 through 3.2.4 describe the development of these assessment tools, which were specifically designed to address environmental effects of toxic pollutants in the water column. 3.2.1 Water Quality Criteria Prior to 1988, toxic substances were only addressed in Washington State's Surface Water Quality Standards (Chapter 173-201 WAC) by a narrative statement that they were not to be discharged to surface waters at concentrations that would adversely affect characteristic water 25 ------- uses, cause acute or chronic effects to aquatic biota, or adversely affect public health. The federal Water Quality Act of 1987 required states to either adopt EPA's numerical water quality criteria (U.S. EPA 1986) or derive their own criteria according to standardized procedures. As a result, numerical water quality criteria developed by EPA for 22 toxic pollutants were adopted by Washington State as standards in 1988. By including these numerical water quality criteria within the state's Surface Water Quality Standards, Ecology received the authority to regulate the discharge of these toxic pollutants on the basis of maximum concentration limits in the receiving water, which represented a significant improvement over the limited ability to regulate their discharge under the previous narrative statement alone. The 1991 Puget Sound Water Quality Management Plan (PSWQA 1990) directed Ecology to update the Surface Water Quality Standards with additional water quality criteria as they are developed or modified by EPA. As a result, numerical criteria for five other toxic pollutants are being considered for addition to the state's Surface Water Quality Standards during the current triennial review of the standards (Ecology 1991). 3.2.2 Whole-Effluent Toxicity Testing One goal of the 1991 Puget Sound Water Quality Management Plan (PSWQA 1990) is to maintain or restore the high quality of Puget Sound waters by controlling the toxicity of wastewater discharges. Control of wastewater toxicity is being addressed through three approaches: 1) the application of all known, available, and reasonable methods of prevention, control, and treatment, collectively referred to as (AKART); 2) compliance with applicable water quality criteria (see Section 3.2.1); and 3) use of whole-effluent toxicity testing to assess the acute and chronic effects of wastewater discharges. Whole-effluent toxicity testing is useful for the control of wastewater toxicity for the following reasons: ¦ Acute and chronic water quality criteria are only available for a small number of the potentially toxic chemicals known to be present in wastewater discharges ¦ Chemical testing may not be able to detect contaminants at concentrations that may cause acute or chronic effects ¦ Regulation on the basis of compliance with individual chemical criteria cannot account for interactions among chemicals in complex wastewater mixtures. The Plan (PSWQA 1990) directs Ecology to require whole-effluent toxicity testing for permitted wastewater discharges regardless of the quality of the receiving water or the minimum water quality standards. Ecology has developed a draft guidance document (Ecology 1990) that 1) describes the use of whole-effluent toxicity testing in assessing the acute and chronic effects of wastewater discharges and 2) specifies the procedures for developing discharge permit limits on the basis of wastewater toxicity. As discharge permits are reviewed for issuance, reissuance, or modifi- cation, requirements will be included for the discharger to conduct whole-effluent toxicity testing. Ecology will require each discharger to characterize the toxicity and variability of its effluent during the first year of the permit term. Toxicity testing should be frequent enough to characterize the effluent thoroughly, and a sufficient variety of species should be tested to 26 ------- provide confidence in the toxicity determinations. If the effluent characterization during the first year of the permit term demonstrates that the effluent is consistently nontoxic, subsequent monitoring requirements may be reduced for some dischargers. Ecology has adopted standardized protocols for testing whole-effluent toxicity (U.S. EPA 1991a,b,c; ASTM 1985). Recommended bioassay species for various kinds of toxicity evaluations include: ¦ Freshwater acute toxicity Cladocerans (Daphnia magna and D. pulex), rainbow trout (Oncorhyn- chus mykiss), and fathead minnow (Pimephales promelas) ¦ Freshwater chronic toxicity Fathead minnow, cladoceran (Ceriodaphnia dubia), and algae (Selenas- trum capricornutum) ¦ Marine water acute toxicity Silverside minnow (Menidia beryllina), sheepshead minnow (Cyprinodon variegatus), and mysid (Mysidopsis bahia) ¦ Marine water chronic toxicity Mysid, silverside minnow, sheepshead minnow, sea urchin (Arbacia punctulata), algae (Champia parvula), and Pacific oyster (Crassostrea gigas). Three alternativeechinoderm species [i.e., green sea urchin (Strongylocentrotusdroebachiensis), purple sea urchin (S. purpuratus), and sand dollar (Dendraster excentricus)] are currently being tested by EPA for use in west coast effluent toxicity testing. These west coast species could replace the currently accepted A. punctulata, which is an east coast species. The number of bioassays to be required by Ecology for effluent characterization depends on the size, type, and location of the discharge. Generally, the number of required bioassays ranges from one to two acute toxicity tests and from two to three chronic toxicity tests. Discharges of a freshwater effluent into a freshwater receiving environment need only be tested using the freshwater bioassays. Saltwater effluent discharges into a saltwater receiving environment need only be tested using the marine bioassays. However, because almost all of the permitted wastewater discharges into Puget Sound are freshwater effluent discharges into a saltwater receiving environment, the bioassays to be used are selected by Ecology's permit writers on a case-by-case basis. Compared with the marine chronic bioassays, the freshwater chronic bioassays are better established, are more readily incorporated into toxicity investiga- tion/reduction evaluations (TI/REs), and avoid the complications associated with controlling and interpreting salinity effects in serial dilutions of freshwater effluent in marine bioassays. It is Ecology's position that the marine acute bioassays are generally as reliable as the freshwater acute bioassays, and therefore may be preferred for freshwater effluent discharges to Puget Sound (Ecology 1990). However, major Puget Sound dischargers generally tend to be assigned 27 ------- marine bioassays and minor Puget Sound dischargers tend to be assigned freshwater bioassays (Sexton 1991, pers. comm.). The results of the acute and chronic toxicity tests conducted during effluent characterization are evaluated to determine whether permit limits need to be established for effluent toxicity. The procedure for establishing water quality-based limits for acute or chronic toxicity incor- porates the total maximum daily load/wasteload allocation (TMDL/WLA) approach of EPA's Technical Support Document for Water Quality-Based Toxics Control (U.S. EPA 1991d). After the initial characterization of effluent toxicity during the first year of the permit term, requirements for subsequent routine monitoring of whole-effluent toxicity will depend on the size, type, and location of the discharge, and on whether permit limits on acute or chronic toxicity were required. In general, only the most sensitive species determined during effluent characterization will be used for routine monitoring. 3.2.3 Monitoring of Wastewater Particulate Material In recognition of the fact that many toxic pollutants in wastewater discharges to Puget Sound are adsorbed on particulate material, one element of the 1991 Puget Sound Water Quality Management Plan (PSWQA 1990) directs Ecology to obtain and review information on particulate contamination in the effluent whenever a discharge permit is issued, reissued, or modified. There are two primary reasons for this directive. First, certain toxic pollutants may be present in the effluent at concentrations that are below conventional analytical detection limits for whole-water samples, but the pollutant may be detected by collecting and analyzing a sample of the particulate fraction. Second, contaminant concentrations on particulates may be used as an indicator of the toxic pollutant load likely to settle out of the water column and accumulate in sediments. Aside from the fact that certain toxic pollutants in effluents may be present in such low concentrations that they are undetectable, the fact that they are primarily associated with particulate material, and not dissolved, may also render them relatively nontoxic in whole- effluent bioassays. Hence, regulation of the potential toxicity of the discharge solely on the basis of whole-effluent toxicity testing may not be sufficient. These toxic pollutants may still be present in sufficient concentration on the particulate fraction that, after settling to the bottom and accumulating in the sediments, they may cause adverse effects on benthic organisms. These toxic pollutants may also become more bioavailable in the environment by shifting phase associations. The challenge, however, in assessing the magnitude of contamination of the particulate fraction is to collect a sufficient amount of particulate material from the effluent to analyze for toxic pollutants. This is especially true for effluents that result from high levels of wastewater treatment (e.g., secondary treatment of municipal wastewater), where the particulate concentration is very low. Simple filtering of the effluent, which may suffice for highly turbid samples, is impractical or ineffective for effluents with a very low suspended solids content. Consequently, Ecology has been considering the use of continuous centrifugation to process large volumes of effluent and collect sufficient particulate material for analysis (Ecology 1988). While this method shows promise, it is not yet ready for routine use in monitoring. Alternatively, the use of sediment traps to collect settling particulate material in the immediate vicinity of 28 ------- wastewater discharges may be considered. A major disadvantage of sediment traps, however, is that they collect settling particulate material from all sources, and not just from the discharge for which permit limits are to be established. Provided that the technical difficulties associated with the collection and analysis of effluent particulate material can be overcome, assessment of particulate contamination shows promise for regulating discharges in such a way that they will not result in excessive levels of sediment contamination. The concentrations of toxic pollutants adsorbed to effluent particulate material may be used in simple screening-level analyses (e.g., comparing the concentrations directly with numerical sediment quality criteria) to determine the likelihood of a given discharge causing unacceptable effects (PTI 1991a). Alternatively, the concentrations of toxic pollutants adsorbed to effluent particulate material may be used in more sophisticated analyses (e.g., as input to contaminant transport and fate models) to analyze the potential for adverse effects (PTI 1991a). Ultimately, such information may be used in establishing limits on the allowable levels of particulate contamination in wastewater discharges, which may lead to additional source control measures, best management practices, limits on the toxicity of the particulate fraction, or limits on the mass loading of toxic pollutants not presently regulated (PSWQA 1990). 3.2.4 Establishment of Site-Specific, Surface Water Cleanup Levels Protective of Human Health MTCA includes provisions for regulating water quality in the vicinity of hazardous waste sites based on the potential for bioconcentration of aquatic contaminants and consequent human health risks from the consumption of contaminated fish and shellfish. The MTCA Cleanup Regulation (Chapter 173-340 WAC) provides human health risk-based algorithms for calculating contaminant concentrations in surface water which would not lead to unacceptable human health risks from such seafood consumption. Cleanup standards for waters that support or have the potential to support fish or shellfish populations may be determined for either carcinogens or noncarcinogens, using equations provided in the regulation and standard exposure assumptions, as described below. For carcinogens, the surface water cleanup level associated with a plausible upper limit estimate of excess lifetime cancer risk of < 10-6 for an individual toxic pollutant is calculated using the following equation and exposure assumptions: r = RISK X ABW x UCF1 x UCF2 X LIFE w CPF X BCF X FCR X FDF X DUR where: Cw = surface water cleanup level (jjlg/L) RISK = acceptable cancer risk level (10-6) ABW = average body weight during the exposure period (70 kg) 29 ------- UCF1 = unit conversion factor (1,000 jug/mg) UCF2 = unit conversion factor (1,000 grams/L) LIFE = lifetime (75 years) CPF = carcinogenic potency factor [as specified in WAC 173-340-708(8)] (kg-day/mg) BCF = fish bioconcentration factor [as defined in WAC 173-340-708(9)] (unitless) FCR = fish consumption rate (54 grams/day) FDF = diet fraction (0.5) DUR = duration of exposure (30 years). To establish surface water cleanup levels for carcinogens using this method, the cancer risks resulting from exposure to two or more hazardous substances may be apportioned between those hazardous substances in any combination as long as the total excess cancer risk does not exceed 10"5. For noncarcinogens, the surface water cleanup level for an individual toxic pollutant that is expected to result in no acute or chronic toxic effects on human health is calculated using the following equation and exposure assumptions: r _ RfD x ABW x UCF1 X UCF2 x HQ w ~ BCF X FCR x FDF where: Cw = surface water cleanup level (/ig/L) RfD = reference dose [as specified in WAC 173-340-708(7)] (mg/kg-day) ABW = average body weight during the exposure period (70 kg) UCF1 = unit conversion factor (1,000 /xg/mg) UCF2 = unit conversion factor (1,000 grams/L) BCF = fish bioconcentration factor [as defined in WAC 173-340-708(9)] (unitless) FCR = fish consumption rate (54 grams/day) FDF = diet fraction (0.5) HQ = hazard index (1). 30 ------- To establish surface water cleanup levels for noncarcinogens using this method, the health threats resulting from exposure to two or more hazardous substances with similar types of toxic response may be apportioned between those hazardous substances in any combination as long as the total hazard index (i.e., the sum of the individual hazard indices) does not exceed 1. These equations are consistent with methods described in Risk Assessment Guidance for Superfund (U.S. EPA 1989b). The point of compliance with surface water cleanup levels calculated using either of the above methods is defined to be the point (or points) where the hazardous substances are released to surface waters, except in the case of mixing zones authorized within a valid discharge permit. 31 ------- 4. MODELING TECHNIQUES Applications of various modeling techniques have proven invaluable in several Puget Sound regulatory programs both for predicting future conditions under various combinations of input variables and for evaluating complex relationships among environmental variables that are not amenable to evaluation through consideration of field-collected data alone. These modeling techniques range in complexity from relatively simple models that focus on a few key processes represented by a single equation to complex computer models incorporating numerous processes. The models that have been used include contaminant transport and fate models, human health risk assessment models, and ecological risk assessment models. This section describes the various modeling techniques and the ways in which they have been employed in Puget Sound. Ocean discharge criteria evaluations conducted for Section 403 discharges may benefit from the application of certain modeling techniques. Application of contaminant transport and fate models is likely to facilitate the interpretation of the environmental impacts of these discharges. Because these models can be run with varying degrees of actual data input, they may be particularly valuable for preliminary screening-level assessments using a minimum of site- specific data. Such assessments may have direct application to determinations of no irreparable harm that must be made upon issuance or reissuance of Section 403 permits when there is insufficient site-specific information to make a determination of no unreasonable degradation. The applications of human health and ecological risk assessment models in Puget Sound regulatory programs may also serve as examples of potential uses of these models for Section 403 evaluations. Both human health and ecological risk assessments are important areas for the development of technical guidance in support of Section 403 (U.S. EPA 1990). 4.1 CONTAMINANT TRANSPORT AND FATE MODELING Several Puget Sound regulatory programs have required modeling of contaminant transport and fate. These modeling applications have included simulating the relationship between contaminant source loading and accumulation of contaminants in the sediments, and simulating sediment processes that may result in natural recovery of contaminated sediments. The models developed for use in these regulatory programs differ substantially in their complexity, ranging from relatively simple analytical box models to multicompartment, numerical mass-balance models. The models can also be run with varying levels of site-specific data, ranging from screening-level analyses that require relatively little site-specific data to detailed analyses requiring considerable site-specific data. Applications of the contaminant transport and fate models are described in the following sections. 32 ------- 4.1.1 Modeling the Relationship Between Contaminant Source Loading and Accumulation of Contaminants in Sediments The Washington State Sediment Management Standards (Chapter 173-204 WAC) include provisions for the establishment of areas in the immediate vicinity of point-source discharges (i.e., sediment impact zones) within which exceedances of the sediment quality standards are allowed. These sediment impact zones are equivalent to mixing zones in the water column, within which water quality standards may be exceeded. Recognizing that some current and future discharges may not be able to meet the long-term sediment quality goals of the Sediment Management Standards, the authorization of sediment impact zones will represent a variance for a specific discharge activity to allow consideration of cost and technical feasibility in meeting the sediment quality standards. In order to implement authorization of sediment impact zones, Ecology required development of a modeling approach that could be used to predict the areal extent and degree of contamination that might be attributable to a given discharge under various discharge scenarios. Various mathematical models were reviewed (PTI 1989a,c) to determine their ability to characterize 1) the spatial extent of sediment contamination adjacent to the discharge point of a contaminated effluent and 2) changes in the level of sediment contamination in response to changes in site-specific conditions (e.g., multiple source loading, sediment accumulation and mixing, and chemical degradation). It was clear that no single model in its present form could address the entire range of source types and receiving water conditions that exist in the Puget Sound area. Instead, a combination of models was needed to provide the flexibility to simulate the full range of environmental conditions expected to be modeled. A sediment modeling approach that simulates initial mixing, farfield transport, sedimentation, and in situ sediment processes (e.g., bioturbation and chemical degradation) was selected for this purpose (Chiou et al. 1991). The modeling approach incorporates two existing models: the Cornell Mixing Zone Expert System (CORMIX) and the Water Quality Analysis Simulation Program 4 (WASP4). CORMIX simulates initial mixing of an effluent in the water column (the nearfield model), and WASP4 simulates longer-term contaminant fate processes (the farfield model). This dual-model approach uses capabilities unique to each model to overcome the limitations of the other. CORMIX is a microcomputer-based expert system that was recently developed as a tool for effluent flow prediction and mixing zone analysis (Akar 1989; Doneker and Jirka 1989). CORMIX can predict the dilution and trajectory of a submerged, single-port discharge (or the discharge from a multiport diffuser) of arbitrary buoyancy (positive, neutral, or negative) into arbitrary water bodies (shallow or deep, stagnant or flowing, uniform or stratified). Water bodies that can be simulated include rivers, lakes, reservoirs, estuaries, or marine coastal waters. CORMIX uses knowledge and inference rules based on hydrodynamic expertise to classify and predict mixing of buoyant jets. CORMIX gathers the necessary data, checks for data consis- tency, assembles and executes the appropriate hydrodynamic simulation models, interprets the results of the simulation in terms of the legal requirements (including toxic discharge criteria), and suggests design alternatives to improve dilution characteristics. CORMIX is capable of handling much more complex modeling scenarios than are other buoyant jet models (e.g., UPLUME, UOUTPLUME, UMERGE, UDKHDEN, and ULINE) previously used by EPA (Muellenhoff et al. 1985). 33 ------- WASP4 is the most recent version of several developmental iterations of the Water Quality Simulation Program. WASP4 is a generalized modeling framework for evaluating contaminant fate in surface water systems, including lakes, rivers, estuaries, and marine coastal waters (U.S. EPA 1988b). Based on the flexible compartment modeling approach, WASP4 can be applied in one, two, or three dimensions, given transport among compartments. WASP4 can also read output files from the link-node hydrodynamic model DYNHYD, which predicts unsteady flow rates of water in unstratified rivers and estuaries given variable tides, wind, and inflow data. A variety of water quality processes can also be addressed with the selection of appropriate kinetic subroutines. The primary goal of the sediment impact zone model is to determine the areal extent and degree of sediment contamination attributable to a discharge (Chiou et al. 1991). This information will then be used to determine whether the predicted sediment contamination would exceed numerical sediment quality criteria (i.e., sediment contaminant concentrations associated with no adverse effects) and, if so, still be below maximum acceptable limits established for sediment impact zones (i.e., sediment contaminant concentrations associated with minor adverse effects) (see Section 6.4). Representative environmental conditions and effluent characteristics may also be used to constrain the definition of acceptable size and sediment contaminant concentration limits for the sediment impact zones. The sediment impact zone model must first simulate initial mixing between the discharge and the ambient water body and then simulate creation of a plume of contamination in the water column (Chiou et al. 1991). In this respect, the sediment impact zone model performs the same function as water quality dilution zone models (Muellenhoff et al. 1985). The sediment impact zone model must also simulate the interactions between surface water, suspended solids, and the sediment bed and associated chemical and physical processes (Chiou et al. 1991). These interactions and processes are usually ignored by water quality dilution zone models. Conse- quently, the spatial and temporal scales for the sediment impact zone and water quality dilution zone models are different. Water quality dilution zone models typically assume steady-state conditions in the water column. The sediment impact zone model must simulate conditions both in the water column and in the underlying sediment bed over a longer time scale. In the following discussion, the zone of initial mixing and dilution is called the "nearfield," and the region beyond the nearfield zone is called the "farfield." The sediment impact zone model consists of two models, a nearfield model and a farfield model, used to simulate processes within these two zones. The sediment impact zone model was selected because of its flexibility, which allows it to be applied to different types of sites, chemicals, and processes (Chiou et al. 1991). Ideally, the area to be covered by the model and important processes to be simulated by the model should be selected on the basis of a site-specific evaluation. Figure 2 shows a hypothetical site where a submerged outfall discharges into an open water body. The crossflow direction of water, the discharge plume, and the particle deposition area are also shown. The nearfield model (CORMIX) simulates the initial mixing process using the following information: ~ Site-specific geometry of the receiving waters (e.g., bounded by shoreline or unbounded; water depth) 34 ------- A. Plan view CROSSFLOW WATER COLUMN PLUME PARTICLE DEPOSITION AREA „SUBMERGED OUTFALL SHORELINE #r:v^ w SOURCE OF THE DISCHARGE B. Cross section SOURCE OF THE DISCHARGE WATER SURFACE PLUME I jj SUBMERGED QUTFAtt PORE WATER FLOW CONTAMINATED SEDIMENT Source: Adapted from Chiou etal. (1991) Figure 2. Hypothetical site of a wastewater discharge. C74437 0991 35 ------- ~ Outfall or diffuser design (e.g., location, dimensions, and orientation) ° Discharge conditions (e.g., rate, density, and concentration) n Ambient flow conditions (e.g., velocity and density gradient). A hypothetical domain of the nearfield model is illustrated in Figure 3A. The output of the nearfield model is a well-defined, steady plume in the water column that is described quanti- tatively by its location, size, and chemical concentration distribution. The area considered by the nearfield model can be specified and adjusted to include the portion of the plume that exceeds a specified concentration. If desired, CORMIX can also compare its output with water quality standards to evaluate possible improvements in outfall design. The farfield model (WASP4) is applied to simulate the interaction between contaminated water and sediment throughout a compartmentalized domain, which can be designed using the results of the nearfield model. This modeling domain generally covers a large area, including the nearfield model area plus the area of surface sediments that may be contaminated. A hypothetical domain of the farfield model is illustrated in Figure 3B. Most of the important chemical and biological processes affecting contaminant concentrations (e.g., sorption, volatilization, and biodegradation), as well as sediment transport, settling, deposition, and resuspension, can be simulated in the farfield model (Chiou et al. 1991). The compartments used in WASP4 can be arranged so that higher resolution is possible near the source. Thus, a more detailed concentration gradient in the water column and the surface sediments can be obtained in the highly concentrated area by using more compartments. A three-dimensional view of the overlapping domains of the nearfield and farfield models is shown in Figure 4. The chemical concentrations in the steady plume predicted by the nearfield model are assigned to corresponding compartments in the farfield model as initial conditions. These conditions are stored as constants in the farfield model by using the WASP4 bypass options for dispersion and advection of dissolved chemicals. Therefore, only solid particles are subject to dispersion and advection in the farfield model, in effect imposing a steady-state link between the supply of contaminants to the plume (simulated by the nearfield model) and the loss of contaminants by particle settling. This technique represents a conservative simplification of actual conditions and makes the link between CORMIX and WASP4 straightforward, without requiring major modifications to either model. This simplification is not far removed from the field situation, where the rate of contaminant discharge is balanced against the rate of contami- nant loss by particle settling and by advection and dispersion of dissolved contaminants. Conse- quently, the final results from the farfield model are reasonably conservative estimates of the areal extent and degree of contamination of the sediment impact zone within the time frame of a discharge permit. WASP4 predicts sediment contaminant concentrations for selected chemical constituents within each model compartment over any specified time period. Typically, the model output is used to predict whether sediment contaminant concentrations will exceed the sediment quality standards within 10 years, and if so, to determine the areal extent and severity of the exceedance (PTI 1991a). This information, along with additional qualitative site-specific information, is used to specify the allowable size of the sediment impact zone during the term of the discharge 36 ------- A. Neariield model CROSSFLOW PARTICLE DEPOSITION AREA PLUME -v# •s» l/l/l/l •s-s-s-.s- S"S"S"S" _ S«S"V*»S« S«Si*S.S DOMAIN OF THE NEARFIELD MODEL SUBMERGED OUTFALL SHORELINE \\ SOURCE OF THE DISCHARGE B. Farfietd model CROSSFLOW PARTICLE DEPOSITION AREA SUBMERGED OUTFALL ¦¦•.¦•.•¦••'¦.•'•¦'PLUME SHORELINE \V • ¦ w SOURCE OFTHE DISCHARGE COMPARTMENTALIZED DOMAIN OF THE FARRELD MODEL Source: Adapted from Chiou etal. (1991) Figure 3. Model domains for impact zone analysis. C744-37 0991 37 ------- CO 00 COMPARTMENTALIZED DOMAIN OF THE FARFIELD MODEL CROSSFLOW ' DOMAIN OF THE NEARFIELD MODEL , WATER SURFACE ZZZZZZZ PARTICLE DEPOSITION AREA SUBMERGED OUTFALL SEDIMENT SURFACE Source Adapted from Chiou et al (1991) Figure 4. Three-dimensional view of the impact zone model. C744-37 0991 ------- permit. Compliance with the sediment quality standards is evaluated over a 10-year period in recognition of the generally slow response time of sediments and because the 10-year period is an administrative convention, defined by two 5-year permit cycles. The potential for long-term exceedance of the sediment quality standards is influenced by the relationship between contaminant loading from the discharge and the assimilative capacity of the receiving environ- ment. Decision-making based on estimated "steady-state" conditions helps to ensure that a discharger is regulated on the basis of the existing discharge and not on the basis of past releases or historical discharges by other facilities. The ability to accurately estimate the areal extent of potential sediment impacts depends on the chemical selected to represent potential impacts and the size of the compartments selected to represent surface sediments. For example, if an inappropriate chemical is selected to represent the facility's discharge (e.g., a chemical that is present at relatively low concentrations and that is not strongly associated with biological impacts), the model output could predict an absence of sediment impacts when impacts would, in fact, occur. The ability of the model to resolve the areal extent of the sediment impact zone is a function of the size of the compartments used to characterize the receiving sediments relative to the predicted size of the sediment impact zone. For example, if a large number of small compartments is used to characterize surface sediment, the spatial extent of the sediment impact zone could be resolved in great detail, but modeling activities would require increased effort to support the greater level of detail. The use of CORMIX and WASP4 to model sediment impact zones is described in greater detail in Chiou et al. (1991) and PTI (1991a). Background information on the CORMIX subsys- tems can be found in Doneker and Jirka (1989) and Akar (1989). Specific guidance on implementing WASP4 is provided by U.S. EPA (1988b). 4.1.2 Modeling of Sediment Recovery Processes Several Puget Sound regulatory programs have required the use of models to estimate the potential for contaminated sediments to recover naturally. Natural recovery of contaminated sediments occurs primarily through three processes: ¦ Burial of contaminated sediments through natural deposition of clean sediments ¦ Mixing of cleaner surface sediments with contaminated deeper sediments by burrowing organisms, ship scour, propeller wash, and natural water currents ¦ Loss of contaminants through biodegradation or diffusion into the overlying water. The rate of natural recovery is also affected by the rate that contaminants are introduced into the environment by ongoing sources. If sources of contaminants to a site have been inactive for at least 5 years and historical sediment chemistry data are available for that time period, it may be possible to estimate natural recovery rates for the site empirically using recent sediment chemistry data. If, on the other hand, sources are ongoing or have only recently ceased, or if historical sediment chemistry data are not available, a mathematical model may be used to estimate natural recovery of the sediments. 39 ------- Approaches to modeling sediment recovery in two Puget Sound regulatory programs are described below. Commencement Bay Superfund Investigations—The Commencement Bay Superfund site is divided into eight problem areas, each of which has sediments contaminated to varying degrees with a wide variety of chemicals (U.S. EPA 1989a). In deciding on the need for sediment remediation within these areas, estimates were first made of the degree of contaminant source control that was expected to be achievable. A relatively simple analytical box model, the sediment contaminant assessment model (SEDCAM), was then used to estimate the natural recovery that would occur in contaminated sediments given specific conditions of source loading, sediment deposition, and chemical-specific loss factors (Jacobs et al. 1988). SEDCAM was used to evaluate whether natural recovery, in conjunction with estimated levels of contaminant source control, would be sufficient to restore areas with contaminated sediments to acceptable levels of sediment quality, or whether active remediation would be required instead. The following processes were incorporated into the SEDCAM model formulation: n Sediment accumulation o Surface sediment mixing ~ Chemical-specific losses due to biodegradation. The model treats surface sediments as a well-mixed box, the size of which is variable and controlled mainly by the depth of the mixed layer (Figure 5). Mixing in the surface sediments arises from the physical activities of benthic organisms, and in shipping waterways, from propeller mixing and ship scour. Material is supplied to the box as freshly deposited material and removed from the box by burial. Biodegradation (or other loss processes) is formulated as a combined first-order loss term. The concentration of a sediment contaminant at some time after natural recovery begins may be estimated using the following equation: -(kS+M)t + C0 X e s where: C = concentration of a contaminant in sediments at time t (mg/kg) M = rate of sediment deposition (gm/cm2-yr) S = total accumulation of sediments in the mixed layer during the period under consideration (gm/cm2) C = M x C -(kS+M)t 1 - e 40 ------- C^xS ACCUMULATION SEAWATER o MIXED LAYER DECAY SEDIMENTS CxS BURIAL C-i = Chemical concentration in recently deposited sediment (mg/g) C = Chemical concentration in surface mixed layer (mg/g) S = Sediment accumulation rate (cm/yr) D = Depth of the mixed layer (cm) kc = First-order decay constant (1/yr) Source: Jacobs etal. (1988) Figure 5. Schematic of processes controlling chemical concentrations in surface sediments. C744-37 0991 41 ------- k = combined first-order rate constant for contaminant loss by in situ decay (yr ') Cp = concentration of the contaminant in particles being deposited in the sediments (mg/gm) t = natural recovery time period (years) C0 = initial contaminant concentration in surface sediments (mg/kg). In applying the SEDCAM model to the Commencement Bay site, a number of simplifying assumptions were made (Jacobs et al. 1988). One generally environmentally protective assumption, which is that a dynamic balance (i.e., steady-state) between source loading and sediment accumulation existed before source control, was applied to all sources or source groups. This assumption was made because limitations in source loading data precluded a more detailed evaluation. This assumption is accurate for areas where source loading has been constant over time, but it tends to overestimate recovery rates where source loading has decreased over time and underestimate recovery rates where loading has increased over time. To simplify the evaluation of the relationship between sources and sediments, and to focus on the most serious environmental problems, indicator chemicals were identified for major sources or groups of sources in each Commencement Bay problem area (Jacobs et al. 1988). Source groups were combined when more than one individual source either could not be distin- guished in an area or contributed a common chemical or group of chemicals. The following information was used to apply the model: ~ The concentration of a contaminant in the surface sediments (C0) was determined from sediment samples collected during the Commencement Bay remedial investigation (Tetra Tech 1985) and early stages of the feasibility study (Tetra Tech 1988a). ~ The depth of the mixed layer and the sediment accumulation rate were estimated from high-resolution excess 210Pb sediment core profiles using the techniques of Carpenter et al. (1981). Sediment mixing acts to attenuate the observed decrease in excess 210Pb activity with depth. The mixed layer is defined as the surface layer of sediments to the depth at which a break in the slope of excess 210Pb activity is observed. Below the mixed layer, the gradient in excess 210Pb activity can be related directly to the half-life (22 years) of 210Pb. The slope of the line relating excess 210Pb activity to sediment depth can be directly translated to a sediment accumulation rate. Sedimentation rates were also estimated from the depth of the sediment layer overlying dredging horizons of known date. Details of this approach are described in Tetra Tech (1987a). ~ Potential losses due to biodegradation (or other first-order loss processes) were evaluated for selected problem chemicals in Commencement Bay. The relative importance of biodegradation would be expected to vary for the different problem chemicals because of their varying susceptibility to biodegradation. Potential 42 ------- losses due to biodegradation were determined from a thorough review of field and laboratory studies. Details of this approach are described in Tetra Tech (1987b). The modeling results provided a useful comparison of the potential of the different problem areas to recover, as well as a rough estimate of the degree of source control necessary to ensure recovery. Based on these modeling results, areas that were expected to recover naturally within 10 years of source control were initially exempt from sediment remedial action (e.g., dredging and confined disposal) (U.S. EPA 1989a). It should be noted that these modeling results were not considered to be completely accurate predictions of sediment recovery, and were therefore subject to verification through periodic monitoring. Should monitoring results indicate that natural recovery is not viable within a reasonable time frame (e.g., 10 years), the need for active sediment remediation will be reconsidered. Washington State's Sediment Management Standards—Analyses of the potential for natural recovery of contaminated sediments will also be conducted under the cleanup standards of the recently promulgated Washington State Sediment Management Standards (Chapter 173-204 WAC). The cleanup standards include provisions for authorization of sediment recovery zones, which are designated areas within which sediment quality standards are exceeded as a result of historical discharge activities. While sediment contamination within sediment recovery zones is sufficiently high that some form of remediation is necessary, the expectation is that natural recovery will be sufficient to restore the sediments to acceptable levels of sediment quality within a reasonable period of time (e.g., 10 years), and that active remediation will therefore not be required (PTI 1991b). Sediment recovery zones may be designated as part of site-specific remedial strategies for areas having sediment contamination in excess of the sediment cleanup standards. The modeling approach selected for the purpose of analyzing the potential for natural recovery had to be capable of addressing more complex situations than did SEDCAM, especially where there may be multiple ongoing contaminant sources in the area and/or the presence of authorized sediment impact zones. WASP4, one of the two models applied in the sediment impact zone model (see Section 4.1.1), is ideally suited to the modeling of sediment recovery processes within authorized sediment recovery zones. The authorization of sediment recovery zones may be considered when (PTI 1991b): ¦ The presence of widespread, low-level contamination suggests that natural recovery should be the preferred alternative for cleanup of a site ¦ Greater environmental harm would result through cleanup of the site than if the site were allowed to recover naturally (e.g., in areas with unique or sensitive resources or areas where biological resources would recolonize very slowly) ¦ The cleanup standards for the site, chosen through consideration of cost, technical feasibility, and net environmental benefits, are higher than the sediment quality standards (i.e., the no-adverse-effects levels of sediment contamination) ¦ Cleanup of the site is not practicable. 43 ------- In any of these situations, sediment recovery zones may be authorized for as large an area as is considered necessary. The goal of a sediment recovery zone is to achieve natural recovery to an acceptable level of sediment quality within 10 years, although sediment recovery zones may be authorized for longer periods if cleanup of the site is still not practicable. The time that will be required to achieve natural recovery may be estimated 1) empirically using sediment chemistry data from the site [provided the source of the sediment contamination is historical and sufficient time (e.g., at least 5 years) has passed so that changes in chemical concentrations can be detected], 2) through the use of relatively simple mathematical models such as SEDCAM (Jacobs et al. 1988), or, more typically, 3) through the use of a more complex model capable of simulating multiple contaminant sources and natural recovery processes. The more complex sediment recovery zone model should be capable of predicting long-term trends in chemical concentrations in surficial sediments and in the areal extent and degree of contamination by incorporating most of the important physical, chemical, and biological processes in surficial sediments. As with the sediment impact zone model (see Section 4.1.1), the sediment recovery zone model must be able to simulate the interactions among surface water, suspended solids, and the sediment bed. Pore water movement in the sediment layer is also an important component of the sediment recovery zone model that is not considered in the SEDCAM model. Among the currently available models, WASP4 meets the sediment recovery zone model requirements described above and is considered is the most suitable for simulating the sediment recovery zone (Chiou et al. 1991). In this application, there is no need for WASP4 to be coupled with CORMIX as it is in the sediment impact zone model, because there is no need to model initial mixing of a discharge. Because a single model is used, simulation of a sediment recovery zone is generally simpler than simulation of a sediment impact zone. One exception would be the situation in which a sediment recovery zone is authorized in the vicinity of ongoing contaminant sources. To simulate sediment recovery in this more complex situation, both CORMIX and WASP4 may be required. Figure 6 illustrates how compartments can be set up in both the water column and the sediment layer for application of WASP4. Higher resolution can be achieved in the more contaminated areas (i.e., hot spots) by specifying more compart- ments. Additional contaminant sources can be introduced into the model by assigning non-zero boundary conditions along the edge of the model domain. Other than differences in the input to the model, operation of WASP4 as the sediment recovery zone model is basically the same as in its use as part of the sediment impact zone model. The use of WASP4 for this purpose is described in greater detail in Chiou et al. (1991). 4.2 HUMAN HEALTH RISK ASSESSMENT MODELING Two Puget Sound programs have employed models to estimate the risks to human health associated with consuming chemically contaminated fish and shellfish. Both the Commencement Bay Superfund investigations and PSDDA have addressed human health impacts potentially resulting from sediment contamination by modeling consumption-based contaminant pathways. In addition, the Commencement Bay investigations employed a model to establish the sediment concentration of PCBs that would be protective of human health through consumption of contaminated seafood. 44 ------- U1 WATER SURFACE CROSSFLOW SEDIMENT SURFACE AREA WITH CONTAMINATED SEDIMENTS MULTIPLE SEDIMENT LAYERS Source: Adapted from Chiou et al. (1991) Figure 6. Three-dimensional view of the sediment recovery zone model. C744-37 0991 ------- 4.2.1 Commencement Bay Superfund Investigations Under the Commencement Bay Superfund investigations, human health risks from seafood consumption were evaluated in a two-phase process. In the first phase, baseline human health risks were estimated for chemicals that had been detected in fish and crab tissue samples from the Superfund site and a Puget Sound reference area. Chemicals that posed significant risks to seafood consumers were identified by calculating carcinogenic risk levels or by comparing measured tissue concentrations with EPA's acceptable daily intake (ADI) values. Risks resulting from seafood consumption at the site were also compared with risks from consuming seafood caught in an uncontaminated reference area of Puget Sound. Contaminants in Commencement Bay tissue samples that posed risks similar to those associated with consumption of seafood from the reference area were not considered for further site cleanup evaluation because it was not considered reasonable to clean up to less than reference area concentrations. The baseline risk assessment completed for the Commencement Bay remedial investigation (Tetra Tech 1985) included a site-specific exposure assessment that consisted of two elements: estimating the exposed population and estimating the rates of fish and crab consumption. An angler survey was conducted to estimate the exposed population and the rate of consumption of fish from the area (Pierce et al. 1987). No site-specific data were available to estimate crab consumption rates. Estimated fish consumption rates ranged from 1 pound/year (1.2 grams/day) to 1 pound/day (454 grams/day). Approximately 93 percent of the exposed population was found to consume 1 pound/month or less, while only about 0.2 percent consumed 1 pound/day or more. These two consumption rates were used as estimates of 1) the maximum potential exposure of a very small part of the population (1 pound/day) and 2) the maximum exposure rate experienced by a high percentage of the population (1 pound/month). Consumption rates for crab were assumed to be equivalent to consumption rates for fish. Health risks were estimated for consumers of Commencement Bay fish and crabs on a chemical-by-chemical basis for carcinogens and noncarcinogens (Tetra Tech 1985). For carcinogens, risks were calculated by multiplying EPA's cancer potency factor for each chemical by the estimated lifetime intake of that chemical. The resultant individual lifetime cancer risk estimates the chance of developing cancer as a result of site-related exposure to the carcinogen over a 70-year lifetime (under the specific exposure conditions assumed at the site). EPA generally considers excess risks in the range of 10-4 to 10~7 as acceptable; however, the 10-6 level is generally used for setting cleanup levels under CERCLA response actions when promulgated criteria are not available (U.S. EPA 1989b). Potential concern for noncarcinogens was evaluated by comparing the estimated lifetime intake rate of a chemical with EPA's ADI value for that chemical. At the 1 pound/month consumption rate, the only carcinogens that exceeded the 10-6 risk level were PCBs and arsenic, and no noncarcinogens exceeded the ADI (U.S. EPA 1989a). Arsenic was not evaluated further because arsenic concentrations in fish tissue from Commencement Bay were not significantly different from arsenic concentrations in fish tissue collected from a Puget Sound reference area. Fish, rather than crabs, were used to set PCB sediment cleanup levels, because health risks associated with consumption of PCBs in crabs were considered to be similar to the health risks associated with consumption of PCBs in fish. 46 ------- The objective of the second phase of the risk assessment was to identify sediment contaminant concentrations that would result in the attainment of reference levels of fish tissue contamination at the Superfund site. It was necessary to evaluate the relationship between sediment contamination and fish tissue contamination so that the effectiveness of alternative chemical-specific sediment cleanup levels in reducing subsequent risks to seafood consumers could be assessed. Details of the quantitative methods used to estimate sediment cleanup levels to protect human health are provided in Tetra Tech (1988a). The establishment of a sediment cleanup level for one group of chemicals (PCBs) to protect human health was based on the calculation of risks relative to reference area conditions. The calculation involved three key determinations and assumptions: ¦ Fish tissue concentration objective—The mean PCB concentration measured in English sole muscle tissue from the reference area (36 /zg/kg wet weight) was selected as the target tissue concentration to be achieved following sediment cleanup at the Superfund site. This PCB concentration in fish tissue would result in an excess individual lifetime cancer risk of 10~5 for a seafood consumption rate of 1 pound/month. ¦ Reference sediment concentrations—Applicable sediment remedial technologies (e.g., removal or capping) were assumed to result in the attainment of reference area sediment PCB concentrations (20 /xg/kg dry weight) at a sediment cleanup site by either dredging contaminated sediments and exposing clean sediments or by capping contaminated sediments with clean material. ¦ Method of quantitative relationships—The equilibrium partitioning method was selected to determine quantitative relationships between sediment contamination and fish tissue contamination. This method assumes that a thermodynamic equilibrium exists between contaminants in sediments and contaminants in fish tissue, and that the relationship can be described quantitatively based on the distribution of a pollutant as a function of fish lipid content and sediment organic carbon content. Because of fish movement and the time required to reach equili- brium, it was also assumed that the mean fish tissue concentrations are a function of the mean sediment PCB concentrations in a problem area (i.e., that as a result of fish movement within a problem area, the fish integrate exposure to sediment contamination, which may be heterogeneous within the problem area). Application of the selected equilibrium partitioning equation to the Commencement Bay data indicated that a mean sediment PCB concentration of 30 /xg/kg dry weight in Commencement Bay would result in attainment of a mean fish muscle tissue concentration of 36 /xg/kg wet weight. Based on this calculation, alternative sediment cleanup levels for PCBs (ranging from 50 to 1,000 /xg/kg dry weight; because other areas of Commencement Bay would have sediment PCB concentrations well below 30 /xg/kg dry weight, it would not be necessary to set the sediment cleanup level as low as 30 /xg/kg dry weight to achieve a mean sediment PCB concentration of 30 /xg/kg dry weight) were evaluated according to the following iterative method, with the intent of achieving an average fish tissue concentration for PCBs similar to reference conditions: 47 ------- 1. A mean reference area sediment concentration (20 ^g/kg dry weight) was substituted for all measured sediment concentrations exceeding a particular sediment cleanup level (e.g., 1,000/*g/kg dry weight). In performing this substitution, it was assumed that all sediments having PCB concentrations exceed- ing the sediment cleanup level would be restored to reference area conditions. 2. An overall postcleanup sediment concentration was calculated as the geometric mean of the estimated postcleanup data set following substitution of all values greater than a particular cleanup level (e.g., 1,000 ng/kg dry weight) with values of 20 /ig/kg dry weight. 3. The mean residual postcleanup sediment concentration was used to calculate the predicted mean fish muscle tissue concentration using the equilibrium partitioning model. 4. The predicted mean fish muscle tissue concentration was compared with the fish tissue concentration objective (i.e., 36 /xg/kg wet weight). Iterative compilation and evaluation of these results indicated that selection of a PCB sediment cleanup level of 150 uglkg dry weight would result in a mean postcleanup sediment concentration of 30 jig/kg dry weight for the Commencement Bay site. This mean postcleanup sediment PCB concentration was predicted to result in attainment of fish PCB concentrations similar to those in Puget Sound reference areas. The health risks associated with seafood consumption from remediated Commencement Bay problem areas would then be similar to the health risks associated with consumption of seafood from reference areas. 4.2.2 Puget Sound Dredged Disposal Analysis Program Under the PSDDA program, sediments proposed for dredging must undergo a series of evaluations in order to be approved for disposal at an unconfined, open-water PSDDA disposal site. As one part of the sediment contamination and toxicity evaluation process (PSDDA 1988a, 1989), sediments exceeding specific sediment chemistry criteria are required to undergo bioaccumulation tests to evaluate the potential for human health impacts before the sediment can be approved for disposal. The level of concern, or trigger value, for requiring the bioaccumula- tion test is set at 70 percent of the PSDDA maximum level (ML) value for sediment chemistry for 28 contaminants of concern. The ML value is a guideline used to define the concentration of a contaminant in dredged material above which there is reason to believe that the material would generally be unacceptable for unconfined, open-water disposal. The ML value for each chemical is set at the highest AET value for that chemical (see Section 3.1.1 for a discussion of AET values and Section 6.2 for a discussion of PSDDA criteria and other applications of the ML value). The bioaccumulation test is conducted using clams (Macoma spp.) exposed to sediment samples over a 30-day period (PSDDA 1988a, 1989). If the contaminant concentrations in the clam tissue at the end of the test exceed target bioaccumulation values for the 28 contaminants of concern, then the sediment is considered unsuitable for unconfined, open-water disposal. 48 ------- These target bioaccumulation values, which, if exceeded, would indicate that unacceptable human health impacts would likely occur, were set based on results from a human health risk assessment model (Tetra Tech 1986). The target bioaccumulation values were derived by estimating daily human consumption rates of fish that could have been exposed at the dredged material disposal site, and then calculating the maximum allowable tissue concentrations in those fish that would not result in unacceptable human health risks. Several simplifying assumptions were made in the development of the target bioaccumu- lation values, including: ¦ The human exposure route is primarily through consumption of fish that are directly exposed to sediments at the PSDDA disposal site ¦ Clams (used in the actual testing) serve as a suitable substitute for fish (used in the human health risk assessment) in assessing the potential for bioaccumulation from sediment ¦ All fish that are consumed come from a single population of fish that have a home range which includes the disposal site ¦ Exposure of the fish population is directly proportional to the area of the home range that is made up of the disposal site ¦ Tissue concentrations in fish are directly proportional to exposure at the disposal site (assuming 100-percent assimilation of chemicals of concern from the sediment into fish tissue). The target bioaccumulation values were calculated from the following equations (Tetra Tech 1986): For carcinogens: c _ (R)(W) (B)(1) where: C = target tissue concentration (mg/kg wet weight) R = reference risk level (10-5) W = reference human body weight (70 kg) B = potency factor for the specific chemical (mg/kg-day)-1 I = average seafood ingestion rate per human (0.05 grams/day). 49 ------- For noncarcinogens: c = (RfD)(W) I where: C = target tissue concentration (mg/kg wet weight) RfD = reference risk dose (acceptable daily intake) value (mg/kg-day) W = reference human body weight (70 kg) I = average seafood ingestion rate per human (0.05 grams/day). Values for potency factors (B), reference doses (RfD), and reference human body weight (W) were those established by EPA (ICF 1985). Under the PSDDA program, the reference risk level (R) was set at 10~5 and the seafood ingestion rate was modified from the results of a recreational angler survey in Puget Sound (Landolt et al. 1985). Using these models, PSDDA developed target tissue concentrations for 28 contaminants of concern, including both carcino- genic and noncarcinogenic inorganic and organic chemicals (PSDDA 1988a, 1989). Based on this approach, only two chemicals (PCBs and arsenic) were considered likely to pose a potential human health problem at contaminant concentrations typically found in Puget Sound organisms. In the case of arsenic, the target tissue concentration is lower than concentra- tions of arsenic in tissue from reference area organisms. Therefore, only if tissue concentrations of arsenic in test organisms are significantly elevated above concentrations of arsenic in tissue from reference area organisms would the proposed dredged material be considered unacceptable for unconfined, open-water disposal (PSDDA 1988a). 4.3 ECOLOGICAL RISK ASSESSMENT MODELING Ecological risk assessment models have been applied to 1) estimate the marine ecological risks associated with dredging and disposal of contaminated sediments and 2) evaluate remedial options for hazardous waste sites that potentially affect marine habitats. Three ecological risk assessment models that have been used to evaluate contaminated sediments in Puget Sound are described below. Because ecological risk assessment is in the early stages of development and the structure and function of ecological systems are generally variable, there is no single standardized risk assessment method that addresses all ecological risk problems. The examples described below include three general categories of ecological risk assessment techniques: ¦ Preliminary ecological risk assessment based on identification of species at risk, food web relationships, and a ranking of ecological hazards 50 ------- ¦ Comparison of site-specific sediment chemistry data with sediment quality values developed from water quality criteria and equilibrium partitioning theory ¦ Probabilistic estimates of population risk based on contaminant transport and fate and biological response models. Ebasco (1990) prepared a preliminary ecological risk assessment of contaminants released from the Harbor Island Superfund site. Parametrix et al. (1991) provided a semiquantitative ecological risk assessment by comparing site-specific sediment chemistry data with derived sediment quality values to identify priorities for sediment cleanup in Elliott Bay. Tetra Tech (1986) developed a framework for conducting probabilistic estimates of ecological risks for use in analysis of dredged material disposal options. Each example of the application of ecological risk assessment techniques is described below. 4.3.1 Harbor Island Superfund Site Harbor Island is located in Seattle, Washington, where the Duwamish River flows into Elliott Bay. The land area of the island, which consists of filled tidelands, is currently used for activities related to commercial services and heavy industry. Ebasco's (1990) preliminary ecological risk assessment of the Harbor Island Superfund site had three components. First, field surveys and literature searches were conducted to identify ecological receptors currently or potentially at risk of exposure to contaminants from the site. The characterization of ecological receptors and potential contaminant exposure at the site included a qualitative analysis of food web linkages and the influence of predator-prey interactions on contaminant exposure. The second component of the preliminary ecological risk assessment involved use of EPA's Exposure Analysis Modeling System (EXAMS) to evaluate contaminant transport and the potential for exposure of ecological receptors at the nearby Kellogg Island Wildlife Refuge. For the third component of the preliminary ecological risk assessment, data describing contaminant concentrations in media, contaminant toxicity, and contaminant transport and fate properties were compiled and used to rank site contaminants according to their potential ecological hazard. The emphasis of Ebasco's (1990) preliminary ecological risk assessment was the hazard- ranking approach, which is based on the work of Halfon and Reggiani (1986). This approach uses decision criteria selected by the investigator to determine which chemicals pose the greatest risk to ecological receptors. Two of the decision criteria (measured chemical concentrations in media and chemical properties influencing bioavailability, persistence, and transport) are related to contaminant exposure potential. The third criterion, contaminant toxicity, is a measure of the chemical hazard. The potential hazards of the chemicals are ranked using vector analysis. For the preliminary ecological risk assessment of the Harbor Island Superfund site, application of the hazard-ranking approach narrowed the focus from 112 potentially toxic contaminants, including pesticides, other organic compounds, and metals, to 5 contaminants that posed the greatest potential aquatic ecological hazard. Because the resources necessary for chemical analysis of media and site-specific toxicity testing are often limited, the hazard-ranking approach developed by Halfon and Reggiani (1986) is a useful tool for screening-level 51 ------- assessments of ecological risk, assuming adequate information is available on chemical properties and toxicity of the contaminants of interest. Although a complete evaluation of the uncertainties, strengths, and weaknesses of such an approach is beyond the scope of this report, an evaluation of this approach is described elsewhere in detail (PTI, in preparation). 4.3.2 METRO'S Toxic Sediment Remediation Project The Municipality of Metropolitan Seattle (METRO) sponsored an investigation of sediment contamination in Elliott Bay and the Duwamish River to identify and prioritize sites for sediment remediation (Parametrix et al. 1991). The purpose of using ecological risk assessment in this study was to determine the relative risks associated with each area of contaminated sediments. The most cost-effective remediation plan was identified by developing a relationship between the cost of remediation and the level of cleanup required to achieve an acceptable risk level. The result was a cost-benefit analysis of remedial alternatives that was used to aid decision-making. Six chemicals were selected as contaminants of concern using the hazard-ranking scheme described by Halfon and Reggiani (1986). Sediment quality values for these contaminants were calculated using partition coefficients and EPA water quality criteria modified to provide varying levels of species protection. According to U.S. EPA (1986), water quality criteria for aquatic life are designed to protect 95 percent of aquatic species if specified concentrations are not exceeded more than once every 3 years. Parametrix et al. (1991) recalculated water quality criteria using EPA methods so that resulting values were protective of 70, 80, and 90 percent of exposed species. For contaminants without EPA water quality criteria, toxicity indices were estimated using interspecies correlation ratios (Suter and Rosen 1988) and existing toxicity data for relevant species. Sediment quality values were calculated from the revised water quality criteria using sediment/water partition coefficients. These sediment quality values represent the sediment contaminant concentrations that would be expected to result in interstitial water concentrations equal to the corresponding water quality criteria. This approach is based on a model that describes the equilibrium partitioning of a contaminant between the organic carbon of sediments and the interstitial water. Use of equilibrium partitioning models to derive sediment quality values is the method preferred by EPA for determining sediment quality criteria (U.S. EPA 1991d). To calculate sediment quality values from water quality criteria, the following equation is used: SQV = Kp X WQC where: SQV = the sediment quality value (/ig/kg dry weight or jtg/kg organic carbon) Kp = the partition coefficient (L/kg dry weight or L/kg organic carbon) WQC = the water quality criterion value (ng/L). 52 ------- The uncertainties, strengths, and weaknesses of this approach are discussed elsewhere (e.g., Becker et al. 1989; Baudo et al. 1990). To characterize the ecological risk associated with contaminated marine sediments, Parametrix et al. (1991) compared their calculated acute and chronic sediment quality values with the geometric mean of the measured sediment contaminant concentrations. This comparison provides an indication of potential impacts to aquatic organisms. However, an ecological risk assessment conducted by these methods should be considered a screening-level risk assessment, because it does not produce estimates of the probability and magnitude of ecological effects, and it does not describe the types of population and community impacts that can be expected to occur. 4.3.3 PSDDA's Evaluation of Dredged Material Disposal Options Tetra Tech (1986) developed a framework for ecological risk analysis for the PSDDA program. A method for estimating the average probability of individual mortality and relating that probability to a population impact index was used in evaluating dredged material disposal options. Other methods were used to directly calculate the population impacts of different disposal scenarios based on population demographics (Vinegar 1983; Gentile et al. 1982, 1983). Tetra Tech (1986) provided guidelines for three levels of risk analysis based on benthic exposure models of increasing complexity. Level 1 was a qualitative analysis of contaminant transport and fate processes, to be used when the results of sediment testing indicate that no test variables are significantly elevated above reference conditions. Level 2 provided a quantitative estimate of exposure assuming steady-state conditions based on the short-term fate of dredged material and associated contaminants. Level 3 involved complex contaminant transport and fate modeling and provided time-variable analysis of contaminant concentrations in media. Quantitative risk models corresponding to Levels 2 and 3 were described for ecological receptors that may be exposed to contaminated dredged material under a variety of disposal conditions. In general, for Level 2 risk assessment, the probability of the mortality of an individual at a certain location is equal to the product of the probability of exposure to a contaminant concentration and the probability of mortality at that concentration: = x Pr(Cx) where: PM = the probability that an individual will die following contaminant exposure PE = the probability of exposure to the contaminated dredged material Pr(Cx) = the probability of mortality as a function of the exposure of an individual to the contaminant concentration (Cx) in the dredged material. The approach described by Tetra Tech (1986) can also accommodate measurement endpoints other than mortality. In addition, spatial and temporal variability in exposure can be considered 53 ------- and included in the risk assessment using Level 3 analysis. The following four approaches are described in Tetra Tech (1986) for Level 3 risk characterization: o Time-averaged exposure and risk assessment—Site-specific information on exposure is used to calculate exposure concentrations during each time interval. The calculated average exposure concentration and probability of exposure (Pg) are used to determine risk as described for Level 2 analysis. e Frequency of unacceptable exposure—Contaminant transport and fate models are used to estimate the exposure concentrations for each time interval. The fre- quency with which ambient concentrations exceed specific toxicity benchmark values (e.g., LC50) is determined by the method summarized by Parkhurst et al. (1981) and is expressed graphically. ~ Time-variable uptake and depuration kinetics—Contaminant transport and fate models are used to estimate exposure concentrations for each time interval. Biokinetic models (e.g., Mancini 1983) of contaminant uptake and depuration by the receptor of concern are used to determine the relationship between percent mortality and exposures to various contaminant concentrations. ° Population modeling—Contaminant transport and fate models are used to estimate exposure concentrations for each time interval. Population models such as Leslie matrices (Vinegar 1983) or life table analyses (Daniels and Allan 1981; Gentile et al. 1982, 1983) and toxicity test results are used to determine the effects of exposures to contaminants on individual fecundity and population growth. A complete description of each of these methods is beyond the scope of this report. However, Tetra Tech's (1986) overall risk assessment approach can be applied using various levels of detail to predict adverse ecological impacts associated with dredged material disposal activities or other contaminant releases into marine habitats. 54 ------- 5. MONITORING GUIDANCE Over the past 6 years, Puget Sound regulatory programs have expanded the attention given to monitoring of permitted wastewater discharges and other environmental monitoring programs in the area. Upon issuance, reissuance, or modification of NPDES permits, increased requirements are being placed on major dischargers to monitor conditions in the receiving environment to more accurately assess the effects these discharges are having on resident organisms. The Puget Sound regulatory programs have made considerable progress in standardizing monitoring protocols to ensure the collection of high-quality monitoring data across programs. Ecology, which has the delegated authority to issue wastewater discharge permits in Washington State, has also developed a manual (Ecology 1989) to assist permit writers with the development of appropriate monitoring programs for individual discharges. Sections 5.1 through 5.3 of this report describe these developments in Puget Sound monitoring programs, which together are improving the ability to detect and interpret impacts on the receiving environment. These developments are also key elements in improving the ability to regulate pollutant releases to the environment. Just as uniform national monitoring guidance was developed under Section 301(h) of the CWA, the development of similar guidance may be considered for Section 403 monitoring programs. National monitoring guidance will provide consistency in developing permit requirements and identify the appropriate levels of monitoring required to support the determina- tions of no irreparable harm and no unreasonable degradation that must be made under Section 403. Just as there has been increased attention given in Puget Sound to monitoring of conditions in the receiving environment, there is also expected to be increased emphasis on monitoring of the receiving environment in the vicinity of Section 403 discharges. For these reasons, consi- deration of recent improvements in Puget Sound monitoring programs may be valuable in the further development of monitoring guidance under Section 403. 5.1 EXPANDED MONITORING REQUIREMENTS FOR MAJOR NPDES DISCHARGES Historically, most monitoring requirements for NPDES dischargers in Washington State addressed only periodic effluent analyses. Sampling and analysis to document conditions in the receiving environment were only rarely required. Monitoring of toxic pollutants was typically limited to relatively infrequent priority pollutant scans of the effluent, if it was required at all. At the direction of the 1991 Puget Sound Water Quality Management Plan (PSWQA 1990), however, Ecology is now expanding the monitoring requirements whenever major NPDES permits are issued, reissued, or modified. The purpose of the expanded monitoring requirements is to assess the effects of the discharge, and especially of toxic pollutants, on the receiving environment. The previous monitoring of effluent alone was appropriate for permits developed from a technology-based approach to regulating pollutant discharges. However, the expansion 55 ------- of monitoring requirements to include assessment of effects on the receiving environment is appropriate for developing effluent limits from a water quality-based approach. Generally, all major NPDES permits will now require the following types of monitoring (PSWQA 1990): ¦ Sampling and analysis for specified variables (including toxic pollutants) in the sediment in the vicinity of each outfall ¦ Separate analyses of the particulate fraction of the effluent from each outfall ¦ Acute and chronic toxicity tests on a sample of the effluent from each outfall (see Section 3.2.4) and on sediments near the outfall ¦ Surveys of the abundance, species composition, and health of biota in the vicinity of each outfall ¦ Water quality monitoring at the boundary of the mixing zone. Modeling of mixing zones to demonstrate compliance with water quality standards may be substituted for monitoring of the receiving water if appropriate field verification studies are conducted. In the event that any of these five types of monitoring is not required of an individual discharger, the justification for not requiring it must be discussed in the fact sheet accompanying the draft permit. Although these monitoring requirements are directed primarily toward the detection of impacts from individual wastewater discharges, Ecology is also developing monitoring requirements for permits that will facilitate calculation of the total quantity of contaminants discharged to Puget Sound. In addition to the five new types of monitoring described above, each major municipal discharger will be required to perform full priority pollutant scans on their effluent at least annually, and more frequently if appropriate. The monitoring requirements are tiered so that if initial (baseline) monitoring indicates no adverse effects, the extent of further monitoring efforts could be reduced (PSWQA 1990). However, if initial monitoring indicates the possibility of adverse effects, more frequent and/or more comprehensive monitoring could then be required. Initial monitoring requirements should be sufficient to ensure that enough data are collected to determine whether additional discharge limits should be established. This may be especially important for toxic pollutants that previously have not been subject to monitoring. 5.2 PUGET SOUND PROTOCOLS Under the auspices of PSEP (see Section 2.5), state and federal regulatory agencies have sought to develop an integrated and consistent approach to managing the actions and events that influence Puget Sound. One of the early areas of concern identified by PSEP was the lack of data compatibility among the various field and laboratory investigations being conducted in Puget Sound. Some of the differences in data compatibility reflected improvements in sample collection and analysis techniques over the years, while others resulted from differences in the preferences or objectives of the individual investigators. The net result of data incompatibility 56 ------- was that environmental managers from the state and federal regulatory agencies were confronted with a patchwork of information that was often of limited value in decision-making. From 1985 to the present, EPA has been funding the development of the Puget Sound Protocols (PSEP 1990) to encourage scientific investigators to use, whenever possible, well- defined and consistent methods for sampling and analyzing environmental data from Puget Sound. The recommendations presented in the protocols pertain primarily to the methods that should be used to measure environmental variables. Recommendations for study design and data analysis are generally not included because those considerations vary widely depending on the objectives of individual investigations. The recommended protocols for each group of variables were developed through a series of workshops attended by representatives from most organizations that routinely measure or use the variables of concern in Puget Sound. The objective of each workshop was to evaluate various methods and, if possible, agree on which methods should be used in the future. Prior to each workshop, the methods used historically in Puget Sound were evaluated and specific items requiring standardization were identified. Each workshop focused on defining acceptable methods and determining which of those methods would provide comparable data. If several otherwise acceptable methods did not provide comparable data, the workshop participants were asked to select only one for future use. After each workshop, draft protocols were developed. To the maximum extent possible, recommendations for the protocols were based on the majority viewpoint of the workshop participants. Draft protocols were then mailed to all workshop participants and other interested parties for review. Following this review, appropriate comments were incorporated into the protocols and the protocols were finalized. The final protocols were bound in a loose-leaf notebook to facilitate future revisions, if necessary, and provided to anyone requesting a copy. To date, 13 chapters of the Puget Sound Protocols have been developed: 1. General QA/QC Considerations for Collecting Environmental Samples in Puget Sound (March 1986) 2. Recommended Protocols for Measuring Conventional Sediment Variables in Puget Sound (March 1986) 3. Recommended Guidelines for Conducting Laboratory Bioassays on Puget Sound Sediments (May 1986, revised edition July 1991) 4. Recommended Protocols for Station Positioning in Puget Sound (August 1986) 5. Recommended Protocols for Measuring Metals in Puget Sound Water, Sediment and Tissue Samples (August 1986, revised edition January 1990) 6. Recommended Protocols for Microbiological Studies in Puget Sound (November 1986) 7. Recommended Guidelines for Measuring Organic Compounds in Puget Sound Sediment and Tissue Samples (December 1986, revised edition January 1990) 57 ------- 8. Recommended Protocols for Sampling and Analyzing Subtidal Benthic Macroin- vertebrate Assemblages in Puget Sound (January 1987) 9. Recommended Protocols for Measuring Conventional Water Quality Variables and Metals in Fresh Water of the Puget Sound Region (January 1990) 10. Recommended Protocols for Fish Pathology Studies in Puget Sound (July 1987) 11. Recommended Guidelines for Sampling Soft-Bottom Demersal Fishes by Beach Seine and Trawl in Puget Sound (June 1990) 12. Recommended Guidelines for Measuring Conventional Marine Water-Column Variables in Puget Sound (May 1991) 13. Recommended Guidelines for Sampling Marine Mammal Tissue for Chemical Analyses in Puget Sound and Adjacent Waters (May 1991). Additional chapters may be developed as the need arises. With regard to chemical laboratory analyses, one important aspect of the protocols that should be mentioned is the identified need for lower detection limits for certain analytes than are routinely achieved by many contract laboratories. It was found that these lower detection limits were required to ensure that concentrations lower than background (or reference area) concentrations could be detected, and because adverse effects of some chemicals have been found at relatively low concentrations. The lower detection limits required by the protocols were considered necessary to be able to measure departures from background conditions and to assess human health and ecological risks. For some analytes, the chemical analytical protocols therefore include method modifications that will allow the analytical laboratories to achieve the required detection limits. The Puget Sound Protocols have received wide distribution both within the region and nationally. Use of the protocols is now being required for most of the Puget Sound monitoring programs conducted by the regulatory agencies, as well as for sampling and analyses conducted by NPDES dischargers, applicants for dredged material disposal permits, and other user groups. 5.3 WASHINGTON DEPARTMENT OF ECOLOGY'S PERMIT WRITERS MANUAL Ecology has recently developed a draft permit writers manual (Ecology 1989) to assist agency staff in writing wastewater discharge permits. The permit writers manual provides NPDES permit writers with a framework for developing monitoring requirements to be included in NPDES permits. The manual is intended to define the minimum standards for permit writing for the water quality certification required by Section 401(a) of the CWA and to ensure statewide consistency in permitting, especially for permits which require best professional judgment determinations. 58 ------- At present, Ecology is expecting a large influx of new permit writers because of the increasing complexity of permits and the expanded monitoring requirements for many of the major dischargers. This manual will serve as an important tool for training new permit writers. With regard to monitoring guidance, the permit writers manual discusses the following general considerations in developing appropriate monitoring requirements: ¦ The objectives of monitoring ¦ Variables to monitor ¦ Frequency of monitoring ¦ Timing of sampling ¦ Locations of sampling ¦ Analytical methods, including QA/QC. The permit writers manual is supplemented by a draft biomonitoring guidance document (Ecology 1990), which describes in detail the use of whole-effluent toxicity tests and the development of permit limits from a water quality-based approach (see also Section 3.2.2). While many of the details in the permit writers manual are specific to the issuance of discharge permits within Washington State, general guidance therein on the development of appropriate monitoring programs may have wider applicability. 59 ------- 6. DECISION-MAKING FRAMEWORKS Each of the major Puget Sound regulatory programs includes a framework of evaluation procedures to assist decision-makers with the sometimes complex process of evaluating the environmental effects of point-source discharges or in-place sediment contaminants. These decision-making frameworks use the sediment and water quality assessment tools and the modeling techniques mentioned earlier, and they also rely on the collection and analysis of monitoring data according to established protocols. This section outlines the decision-making frameworks for each of the major Puget Sound regulatory programs and describes their use of assessment tools and modeling techniques, as appropriate. Although there are relatively minor differences among programs in the ways these elements are applied, there is a common philosophy in their basic approaches. For example, there is a common reliance on chemical sediment quality criteria as the basis for decision-making, but in each of the programs concerned with sediment quality, allowance has been made for overriding the sediment quality criteria with site-specific biological tests (e.g., through the use of sediment toxicity tests or assessments of benthic macroinvertebrates). It is expected that future development of technical guidance under the Section 403 program will require the development of a decision-making framework for conducting the evaluations required under Section 403 in a logical, cost-effective, and nationally consistent manner. The decision-making frameworks of the Puget Sound regulatory programs are in many ways similar to the decision-making framework that is likely to be developed for Section 403 evaluations, because many of the same or similar assessment tools and modeling techniques used in the Puget Sound programs may be used in Section 403 evaluations as well. Also, the diversity of point- source discharges covered under Section 403 makes it highly likely that a decision-making framework developed for that program will incorporate tiering of the evaluation procedures. Hence, by describing the ways in which the evaluation procedures are tiered in the Puget Sound regulatory programs, the experience gained in those programs may be applied in devising a cost- effective and efficient decision-making framework for Section 403 evaluations. 6.1 COMMENCEMENT BAY SUPERFUND INVESTIGATIONS Commencement Bay was named as a National Priorities List site for cleanup under Superfund in 1981 largely because of sediment contamination and associated biological impacts. At the time, there were few comprehensive studies of contaminated estuarine sites that could be used as a model for designing site investigations or for determining what constituted a level of contamination that represented a risk to the aquatic environment. Several study designs and decision-making frameworks were developed to identify problem areas objectively and to rank the areas in terms of priority for remedial action (PTI 1989b). Empirical information on the degree and extent of sediment contamination and biological effects formed the basis for identifying and ranking problem areas. There were seven major steps in the decision-making process for identifying and evaluating problem areas: 60 ------- ¦ Characterize sediment contamination, sediment toxicity, and in situ effects on indigenous organisms in various areas throughout Commencement Bay ¦ Quantify relationships among sediment contamination, sediment toxicity, and in situ effects on indigenous organisms ¦ Apply action levels to determine problem areas ¦ Determine problem chemicals in problem areas ¦ Define spatial extent of problem areas ¦ Evaluate pollutant sources contributing to problem areas ¦ Evaluate, prioritize, and recommend problem areas and sources for potential remedial action. To characterize the environmental conditions in Commencement Bay, the following types of data were collected: ¦ Bulk sediment samples were analyzed to determine contaminant concentrations, grain-size distribution, organic carbon content, and sulfide content. Sediment contamination was evaluated relative to sediment contaminant concentrations in Puget Sound reference areas. Chemicals of concern were identified in the early stages of the investigation as chemicals with concentrations exceeding the highest concentration (or detection limit) reported for any Puget Sound reference area. Individual chemicals that exceeded 80 percent of the concentrations determined for all Commencement Bay stations were considered to be of greatest concern. ¦ English sole (Parophrys vetulus) muscle tissue and cancrid crabs (Cancer spp.) muscle tissue were analyzed to determine concentrations of bioaccumulated contaminants. Bioaccumulation data were evaluated using standard EPA risk assessment tools to determine whether bioaccumulation levels in Commencement Bay posed a significant threat to human health from seafood consumption (see Section 4.2). ¦ Sediment toxicity was tested using the amphipod (Rhepoxynius abronius) mortality test and the oyster (Crassostrea gigas) larvae abnormality test (see Section 3.1.2). The amphipod mortality toxicity test was used to measure a lethal response to adult organisms and the oyster larvae abnormality bioassay was used to measure a sublethal response to larval organisms. Results of these toxicity tests were compared with results of tests that used reference area sediments to determine whether there were significant (P< 0.05) increases in mortality at Commencement Bay stations. ¦ Abundances of major benthic macroinvertebrate taxa (i.e., Polychaeta, Crustacea, and Mollusca), as well as total macroinvertebrate abundance, were determined (see Section 3.1.2). Abundances of major benthic taxa were compared with refer- ence area abundances to determine whether there were significant (P<0.05) decreases in abundances at Commencement Bay stations. 61 ------- ¦ Prevalences of liver lesions in English sole from Commencement Bay were determined and compared with those in English sole from reference areas. English sole were selected for histopathological evaluation because they live in close association with sediments and they prey on benthic macroinvertebrates. 6.1.1 Characterizing Problem Areas Several data interpretation approaches were developed during the Commencement Bay Superfund investigations to characterize problem areas (PTI 1989b). These included develop- ment of elevation above reference (EAR) values, action assessment matrices, and action-level guidelines. EAR Values—EAR values were developed to rank areas in a preliminary fashion based on the magnitude of observed contamination and biological effects relative to reference area conditions. EAR values are a ratio between the value of a variable at a site in Commencement Bay and the value of the same variable at a reference site. For most variables, the average value at the study site was divided by the average value at the reference area to obtain each EAR value. Action Assessment Matrices—The EAR values were organized into an "action assessment matrix" to compare study areas or sampling stations. A hypothetical action assessment matrix is presented in Table 2. These matrices display the EAR value for each environmental indicator for each study area, indicate whether the EAR value is significant, and provide the reference value on which the EAR value is based. Action-Level Guidelines—Action-level guidelines were developed and applied to the action assessment matrices to identify study areas of concern and guide subsequent actions. The following action-level guidelines were developed for this purpose: ¦ Significant EAR values for three or more environmental indicators identified a problem area requiring evaluation of sources and potential remedial action. ¦ For any two environmental indicators showing significant EAR values, the decision to proceed with source control and remedial action depended on the combination of indices and the magnitude of the EAR values. ¦ When the EAR value for only one indicator was significantly elevated, a problem area might be defined when the magnitude of the environmental indicator was sufficiently elevated (e.g., above the 80th percentile for all study areas for sedi- ment chemistry, greater than 50-percent mortality for the amphipod bioassay, 95 percent or greater depression in the abundance of a major benthic taxon, or, for bioaccumulation, prediction of > 1 additional cancer case in the exposed 62 ------- TABLE 2. HYPOTHETICAL EXAMPLE OF ACTION ASSESSMENT MATRIX0 EARb Values for Study Sites Reference Indicator A B C D E Value Sediment contamination 1,300^ 4$ 800 ' 7$ 8 1,000 ppb Toxicity 2.0 10-0 4.5 2.2 10% mortality Bioaccumulation $00 20 1*100 200 ; 13 10 ppb Pathology £.2 2.6 8-0 2*8 2.0 5% prevalence Benthic macroinvertebrates 4*0 1.2 $-0,:-: 1.3 1.1 60 individuals/m2 a EAR values for indicator variables are shown for Sites A-E. Benthic macroinvertebrate factors represent the reduction in numbers of individuals at the study site relative to the reference site. Factors for all of the other indices represent increases relative to the reference site values shown. b EAR - elevation above reference c Shaded values indicate EAR value for the specified area is significantly different from reference value. 63 ------- population for carcinogens or exceedance of the ADI value for noncarcinogens). Fish histopathology alone was insufficient to define a problem area. 6.1.2 Ranking Problem Areas and Problem Chemicals Problem areas and problem chemicals were ranked in two stages (PTI 1989b). The initial ranking of problem areas was performed to identify the worst-case contaminated areas. Refinement of the initial ranking and identification of priority contaminants relied on the development of quantitative relationships between sediment contamination and biological effects. Initial Ranking of Problem Areas—The initial ranking of problem areas was based on a systematic method of assigning scores to sampling sites based on the magnitude and significance of individual chemical or biological indicators and the number of significantly elevated indicators. The ranking method was developed independently of the action-level guidelines; however, the same indicators were used. Table 3 presents criteria for scoring problem areas in terms of priority for source evaluation and remedial action. Based on these criteria, a higher priority was assigned to an area with many elevated EAR values than to an area with few elevated EAR values. Because the magnitudes of the individual EAR values were assumed to represent relative environmental hazards, areas with higher values were scored higher. Average and worst-case conditions were used to rank areas. The average method was most useful for identifying areas with widespread contamination, whereas the worst- case method was useful for identifying the most severely contaminated areas, even if they were small in size. Scoring categories were defined for metals, organic compounds, toxicity tests, benthic macroinvertebrates, fish muscle bioaccumulation, and fish liver pathology. A category was not defined for crab bioaccumulation because these data were inadequate to support meaningful quantitative analyses. In cases where all variables were measured, the maximum possible score for sediment contamination and biological effects was 24. Scores were derived for broad geographic zones using various approaches, including sediment chemistry alone, the average number and magnitude of biological effects, and the maximum value for contamination or biological effects. Refinement of Problem Area Ranking and Identification of Problem Chemicals—The refinement of problem area ranking was based on the development of quantitative relationships between sediment contaminant concentrations and biological effects. No systematic approach was available to quantitatively evaluate the relationship between chemical concentrations and biological effects. The AET approach (Section 3.1.1) was initially developed as a method to rank problem areas in Commencement Bay. Problem areas were identified within the geo- graphic zones described above based on a comparison of sediment contaminant concentrations with AET values. High priority areas were identified where one or more contaminants exceeded one or more AET values. 64 ------- TABLE 3. SUMMARY OF RANKING CRITERIA FOR SEDIMENT CONTAMINATION, TOXICITY, AND BIOLOGICAL EFFECTS INDICATORS Criteria Score Observation Metals (one or more) 0 Concentration not significant 1 Significant; EAR <10 2 Significant; EAR 10-<50 3 Significant; EAR 50- < 100 4 Significant; EAR > 100 Organic compounds (one or more) 0 Concentration not significant 1 Significant; EAR < 10 2 Significant; EAR 10- < 100 3 Significant; EAR 100-<1,000 4 Significant; EAR >1,000 Toxicity8 0 No significant bioassay response 2 Amphipod or oyster bioassay significant 3 Amphipod and oyster bioassay significant 4 ^40 percent response in either bioassay Macroinvertebratesb 0 No significant depressions 1 1 significant depression 2 2 significant depressions 3 ^3 significant chemicals 4 a1 variable with > 95-percent depression Bioaccumulation (fish muscle) 0 No significant chemicals 1 1 significant chemicals 2 2 significant chemicals 3 ^3 significant chemicals 4 Significant bioaccumulation of ^ 1 chemical posing a human health threat0 Fish pathology (liver lesions)d 0 No significant lesion types 1 1 significant lesion type 2 2 significant lesion types 3 s3 significant lesion types 4 s 5-percent prevalence of hepatic neoplasms Maximum Possible Score 24 a Toxicity based on amphipod mortality and oyster larvae abnormality bioassays. b Variables considered were total macrobenthic abundance, total number of taxa, Amphipoda abundance, and dominance. c Action level guidelines. d Lesions considered were hepatic neoplasms, preneoplastic nodules, and megalocytic hepatosis. Source: PTI (1989b) 65 ------- Problem chemicals were defined as any chemical that exceeded one of the three AET values (i.e., those based on the oyster larvae and amphipod toxicity tests, or benthic macroinvertebrate abundances) for that chemical at any station within a problem area. Problem chemicals were further prioritized into three categories: ¦ Priority 1 (highest priority)—Chemicals present above an AET value with a spatial distribution (i.e., concentration gradient) corresponding to observed gradients in sediment toxicity or benthic effects ¦ Priority 2 (intermediate priority)—Chemicals present above an AET value at more than one station in a problem area with no apparent relationship to toxicity or benthic effects gradients, or insufficient effects data were available for evaluation of gradients ¦ Priority 3 (lowest priority)—Chemicals present above an AET value at only one station within a problem area. 6.1.3 Technical Approaches Developed for Site Management Problem areas were further prioritized for subsequent action based on the environmental hazard indicated by contamination and adverse biological effects, the areal extent of the problem area, and the confidence that major sources of problem chemicals had been identified (PTI 1989b). Problem chemicals were further ranked to focus source control efforts. This ranking was based on the relative magnitude of the concentration of each chemical in sediments, the spatial extent of sediments exceeding AET values, the proximity of sediment contamination to potential sources, and documentation of the problem chemical in source discharges. The significance of site contamination was also evaluated by assessing public health risks associated with the consumption of contaminated seafood (this assessment is described in more detail in Section 4.2.1). Because the ultimate objective of the Commencement Bay studies was to determine a course of action for Superfund cleanup at the site, there were several other significant tasks undertaken. The task most relevant to the Section 403 program was the development of sediment quality objectives and remedial action levels (U.S. EPA 1989a). Sediment quality objectives based on environmental risks were established as the lowest AET value for three biological indicators (oyster larvae and amphipod toxicity tests or benthic macroinvertebrate abundances). In addition, a sediment quality objective based on human health risks was established for PCBs (see Section 4.2.1). If the concentrations of all sediment contaminants were below the sediment quality objectives, the sediment was judged not to have any adverse ecological or human health effects. Simplified decision-making guidance was developed to integrate information on contaminant sources and natural recovery into the selection of a preferred remedial alternative for each Commencement Bay problem area (Tetra Tech 1987b). Natural recovery processes were taken into consideration in establishing site-specific sediment remedial action levels to discriminate sediments that would be allowed to recover naturally from sediments that would require active remediation. For sediment contamination in which the source was historical only, the need for 66 ------- active sediment remediation was determined primarily on the basis of whether natural processes such as sedimentation and biodegradation would result in contaminant concentrations lower than the sediment quality objectives within a 10-year period (Figure 7). For sediment contamination whose source was ongoing, the need for active sediment remediation was determined based on the predicted success of source control efforts and natural recovery processes (Figure 7). These determinations were made using a mathematical model (SEDCAM), which incorporated both the predicted effects of source control and natural recovery processes (see Section 4.1.2). 6.2 PUGET SOUND DREDGED DISPOSAL ANALYSIS PROGRAM Under PSDDA, decisions must be made about the suitability of dredged material for unconfined, open-water disposal at designated sites within Puget Sound. All decisions about the quality of dredged material that will be allowed to be disposed of in Puget Sound are predicated on the understanding that some biological impacts may occur within the disposal site. The PSDDA agencies operationally define the degree of allowable impacts as "Site Condition n," in which some minor adverse effects on biological resources may occur (PSDDA 1988a). Minor adverse effects are those that may affect some species within the disposal site as a result of long- term exposure to sediment contaminants. Only sublethal effects are expected to occur, however, and lethal effects would not be allowed. The PSDDA agencies use a three-tiered decision-making framework (Figure 8) to characterize dredged material (PSDDA 1988a, 1989). The tiered approach was developed to ensure consistent and predictable application of the dredged material disposal guidelines. One of the primary advantages of tiering the testing requirements is that analytical costs can be reduced by efficiently allocating resources for testing based on the relative regulatory concerns that might be associated with an individual dredging project. The three tiers of the decision- making framework are: ¦ Tier 1—Assess existing sediment information from the project area to determine whether testing is required ¦ Tier 2—Conduct chemical testing, if necessary ¦ Tier 3—Conduct biological testing, if necessary. This decision-making framework is designed to sequentially determine 1) whether sampling and analysis of the dredged material is necessary to rule on a permit application, 2) what types of analyses (chemical or biological) are needed to characterize the dredged material, and 3) whether the dredged material meets the requirements for unconfined, open-water disposal at a PSDDA site. The PSDDA evaluation procedures and decision-making framework are applied on a project-specific basis. In developing general procedures for use throughout Puget Sound, it was not possible to consider the unique aspects of all individual projects or to assess all the possible outcomes that might arise from the test results. Consequently, PSDDA considers best professional judgment to be an essential element in reaching project-specific decisions, and the 67 ------- CT> 00 Recovery In Acceptable Time Frame? No Yes No Source Control Effective? Yes Recovery In Acceptable Time Frame' No Yes Evaluate) Source Control and Sediment Remediation Evaluate Source Status Evaluate Source Control and Periodic Dredging Model Sediment Recovery for Representative Chemicals Ongoing Evaluate Feasibility of Source Control No Action Evaluate Sediment Remediation Model Success of Source Control Evaluate Source Control Historical Source PTI (1989b) Figure 7. Evaluation of contaminant source status, source control, and natural recovery in the selection of remedial alternatives tor Commencement Bay. C744-37 0991 ------- Are chemical data adequate? NO YES YES NO Are all chemicals of concern below ^screening level?. YES (1) NO Are any chemicals of concern above maximum level? YES YES (2) NO NO NO YES Are disposal guidelines met? Are disposal guidelines met? NO NO, YES YES ^ Permit applicant's^ option to conduct special ^^biologxal tests?^^ ^Permit applicant's option to conduct special ^^biological tests TIER2 Conduct Chemical Tests MATERIAL IS SUITABLE FOR UNCONFINED, OPEN-WATER DISPOSAL MATERIAL IS UNSUITABLE FOR UNCONFINEO, OPEN-WATER DISPOSAL TIER 1 Existing Segment Toxicity Information Special Biological Tests • Amphipod • Juvenile Polychaete • Sediment Larval (3) • Microtox (4) • Bioaccumulation (5) • Other Tests (6) TIER 3 Standard Biologic*) Test* • Amphipod ' - Juvenile Polychaete • Sediment Lewd (3) • Mierotox (4) ' . • Bioeccumuiatfon (5) 1 Biological testing may still be required if there is reason to believe that the sediment is highly anomalous and may represent a significant environmental risk even though all chemicals of concern are below screening levels for unconfined, open-water disposal. 2. Standard Tier 3 biological testing can still be conducted when only a single chemical of concern exceeds the maximum level by <100%. Biological testing of material with chemical levels above maximum level is allowed as an option of the permit applicant (see footnote 6). 3. The sediment larval test is required whenever biological testing is necessary; the water column larval test is only required when water column effects are of concern. 4. Microtox testing is required only for nondispersive site Section 401 reviews; it is not required for nondispersive site Section 404 evaluations nor for 401 or 404 evaluations at dispersive sites. 5 The chemical screening level that determines when bioaccumulation testing is required is higher than for other biological testing, 6. Special biological testing will include additional, more sensitive sublethal biological tests. Source; PSODA (1988a) Figure 8. PSDDA three-tiered decision-making approach. C744-37 0991 69 ------- evaluation procedures (including the disposal guidelines) were designed to be sufficiently flexible to allow full consideration of all pertinent project-specific factors. The types of analyses required in each tier of the PSDDA decision-making framework are described in greater detail in the following sections. 6.2.1 Tier 1 - Review of Existing Information Section 404(b)(1) of the CWA requires that existing information on a proposed dredging area be reviewed to establish whether a "reason to believe" exists that sediments may be contaminated. The information used to determine whether an area may be contaminated includes past research studies, historical data on dredged material from the area, records of spills in the area, NPDES permit records, number and type of industries located in the vicinity, groundwater contamination extending into the area to be dredged, and the probability of surface runoff into the area (PSDDA 1988a, 1989). If there is a reason to believe that the proposed dredging area is contaminated, site-specific chemical and biological data will need to be collected. In some cases, it may be possible to use previously collected data to characterize the sediments in a proposed dredging area. The PSDDA agencies have developed "recency" guidelines to determine the adequacy of existing information for dredged material characteriza- tion. These recency guidelines are based on the number and operating status of chemical contaminant sources near the site to be dredged, an assigned area ranking (e.g., high, moderate, or low likelihood of contamination), and whether the sediments are surface (<4 feet below the existing bottom) or subsurface (>4 feet below the existing bottom) (PSDDA 1988a, 1989). A depth of 4 feet was adopted by PSDDA as an operational definition to delineate between surface and subsurface sediments because the clamshell dredge commonly used in Puget Sound cuts to a depth of 4 feet. For sites near active chemical contaminant sources, sediment data are only considered valid for 2 years from the date of sampling, unless a spill has occurred. In all other areas, sediment data are considered to be valid for a period of 5-7 years, unless existing information indicates that changes in sediment contamination may have occurred since the last sampling period. 6.2.2 Tier 2 - Chemical Testing If existing information is not available or is inadequate, additional detailed information is required to determine the suitability of the dredged material for disposal at a PSDDA open-water site (PSDDA 1988a, 1989). Sediments planned for dredging must be sampled and analyzed for the PSDDA chemicals of concern (Tier 2) and, if necessary, biological tests must be conducted (Tier 3). The PSDDA chemicals of concern include potentially toxic metals and organic compounds that have historically been found in Puget Sound sediments or that were known to be associated with manufacturing processes located in the Puget Sound area. The list of PSDDA chemicals of concern currently includes 9 metals and 49 organic compounds. Additional site- specific chemicals of concern may be added to this list at the discretion of the PSDDA agencies (e.g., if special types of industries located in the vicinity of a proposed dredging area discharge chemicals not on the chemicals of concern list). 70 ------- The PSDDA agencies have ranked general areas of Puget Sound based on their perceived likelihood of having significant sediment contamination (PSDDA 1988a, 1989). Project size and the ranking of the general area in the vicinity of the proposed dredging project affect the need for testing and the types of tests required. The number of samples required for testing increases with the size of the project and with a change in ranking from low to moderate to high. Reduced testing requirements were developed by the PSDDA agencies for small projects because such projects, by themselves, represent a low risk for unacceptable adverse effects at the disposal site. For relatively large projects, the permit applicant may elect to perform a partial characterization of sediments contained in the proposed dredging area, if the applicant is of the opinion that the project area is overranked. Partial characterization is based on chemical analysis of a limited number of samples. If this analysis indicates that the area has been overranked (i.e., concentrations of chemicals are actually less than previously thought), then the ranking of the area can be reduced prior to full characterization. A reduction in ranking can reduce the overall cost of mobilization, sampling, and testing. However, cost reductions are usually not substantial for small projects. If partial characterization data for a given sampling station indicate a need for increasing the ranking, the PSDDA agencies will rerank the area in the vicinity of that station and full characterization will be conducted on the basis of the new rank. To determine the need to conduct Tier 3 testing, two kinds of chemical criteria, screening level (SL) values and maximum level (ML) values, were established for each PSDDA chemical of concern (PSDDA 1988a, 1989). The SL values are guidelines used to define the concen- tration of a chemical in dredged material below which there is no reason to believe unacceptable adverse impacts would result from the unconfined disposal of the material at an open-water disposal site. If all chemicals of concern in the dredged material are below their respective SL values, the material is suitable for open-water disposal without further testing, unless other available information (e.g., the known presence of potentially toxic sediment contaminants for which there are no SL or ML values) indicates a reason to believe the dredged material may be unacceptable for open-water disposal. The SL value for each chemical was set at a numerical value that is 10 percent of the highest available AET value for that chemical (see Section 3.1.1 for a discussion of AET values) providing that the resulting value 1) exceeds the mean concentration for the chemical in relatively uncontaminated reference areas in Puget Sound and 2) is lower than the lowest available AET value for that chemical. If the SL value based on 10 percent of the highest AET value was below the mean concentration found in sediments from reference areas, then the SL value was adjusted to the mean reference area value. If the SL value based on 10 percent of the highest AET value was higher than the lowest AET value, then the SL value was adjusted to the lowest AET value. The ML value is a guideline used to define the concentration of a chemical in dredged material above which there is a reason to believe that the material would generally be unaccept- able for unconfined disposal at an open-water disposal site. The ML value for each chemical was set at the highest available AET value for that chemical. If the dredged material has one or more contaminant concentrations above the SL value for any chemicals of concern, but less than the ML value, biological testing (Tier 3) is required. Although sediments having concentrations of chemicals above the ML value are normally considered unsuitable for unconfined, open-water disposal, they could be subjected to biological testing (Tier 3) at the discretion of the permit applicant to determine whether the sediment is suitable for such disposal. 71 ------- In such instances, the results of biological testing may override the results based on sediment chemistry alone. 6.2.3 Tier 3 - Biological Testing The biological testing requirements developed by the PSDDA agencies were designed to address both sediment toxicity and potential water column effects (PSDDA 1988a, 1989). Testing includes evaluation of sediment toxicity using the following sediment bioassays (see Section 3.1.2 for additional information on these sediment bioassays): ¦ Amphipod mortality test ¦ Juvenile polychaete (Neanthes) mortality test ¦ Larval [bivalve (oyster or mussel) or echinoderm (sand dollar or sea urchin)] abnormality test ¦ Microtox® bioluminescence test. If the sediment concentration of any chemical of concern because of human health risks is above a critical value (i.e., 75 percent of the ML values for chemicals that might pose a hazard to human health), the PSDDA evaluation procedures require a bioaccumulation assessment. The bioaccumulation assessment requires a chemical tissue analysis of the bivalve Macoma spp. after it has been exposed to the dredged material in a laboratory bioassay. The resulting tissue concentrations are compared with target tissue concentration values for the chemicals that might pose a hazard to human health. The chemical concentrations found in the tissues of test organ- isms are interpreted using guidelines developed from EPA risk assessment procedures, as described in Section 4.2.2. The biological tests were chosen because they were available, sensitive, and generally accepted, and because they provided interpretable endpoints (e.g., mortality or quantitative tissue concentrations that can be incorporated into a human health risk assessment) for assessing sediment toxicity and the effects of dredged material disposal on the environment. Multiple tests are required to provide diversity of types of toxic responses and to assess the different sensi- tivities of the various species to different chemicals. The responses of organisms from the biological tests are compared with the responses from the control and reference sediments to determine whether the dredged material is suitable for unconfined, open-water disposal. The determination of significant response for a bioassay is outlined in Figure 9 and involves two conditions: first, that the total mortality in the tested dredged material must be greater than 20 percent (absolute) over control results, and second, that the results of a statistical comparison between mean test and mean reference responses must show a statistically significant difference (at P< 0.05). The interpretation of biological test results differs slightly between the evaluations conducted by the federal agencies under the authority of Section 404(b)(1) of the CWA and the evaluations conducted by the state agencies under the authority of Section 401 of the CWA (Figure 10). Test interpretation for the Section 404(b)(1) evaluation is based on the analysis of the amphipod toxicity, larval abnormality, and juvenile polychaete toxicity tests. The material proposed for dredging is considered unsuitable for unconfined, open-water disposal if either bioassay results in a significant failure (i.e., "single hit") or if at least two bioassays fail based 72 ------- in * 0 UJ 1 O -I o a K > t _i « 3 o (0 * u id Z o UI > s a. a UJ CONTROL SINGLE HIT TWO HIT For the pertinent bioassays (1), are quality control limits exceeded? DATA FROM BIOASSAY ARE NOT ACCEPTABLE FOR DECISION-MAKING (2) BIOASSAY IS A NON-HIT, AND IS NOT CONSIDERED FURTHER For any test bioassay is response >20% over control? For any bioassay, Is the test response >30% over reference and statistically significant over reference? (3,4) MATERIAL IS NOT SUITABLE FOR UNCONFINED, OPEN-WATER DISPOSAL For each test sediment, are two or mors bioassays statistically significant over reference? (5) MATERIAL IS NOT SUITABLE FOR UNCONFINED, OPEN-WATER DISPOSAL MATERIAL IS SUITABLE FOR UNCONFINED, OPEN-WATER DISPOSAL 1. At this step in the flow chart, the Section 40* bioassays are amphipod and |uvenile polychaete species; the Section 401 bioassays include those tests plus the sediment lama] bioassay. The Section 404 water column bivalve larval bioassay Is not In this flow chart [Mlcrotox, which Is a Section 401 test, enters In a later step (two hit)]. 2. If any bioassay fails quality control limits, it generally must be rerun; unless the PSDDA regulatory agenaes deade to Interpret suitability based on remaining test results. 3. Generally a single-tailed Student's f-comparlson of mean lest sediment response versus mean reference sediment response (Ho: they are equal), alpha level of £ 0.05. 4. This decision block refers to nondispersive sites (Commencement Bay, Port Gardner, Elliott Bay. Andersen/Ketron Islands, and Belllngham Bay). For dispers we sites (For Angeles, Pon Townsend, and Rosano Straits), the single hit rule is >10% over reference and statistically significant for the arrphipod and |uvenile polychaete species test, and >15% over reference and statistically significant for the sediment larval test. 5. This applies to nondtspersive sites and the two hit case. Microlox Is an additional Section 401 test that must be considered at this point. Mlcrotox results of the test sediments must be statistically significant Irom reference results and >20% below control response to count as a hit Source: PSDDA (1988a) Figure 9. Summary of biological testing requirements. C744-37 0991 73 ------- i SECTION 404 (bXV EVALUATION TIER 3 Conduct Biological Tests • Amphipod • Juvenile Polychaete • Sediment Larval (1) • Microtox (2) • Bloaccumulation (3) i Is toxicity tn amphpod or juvenile polychaete test >30% over, and statistically different from, reference'' Are both the amphpod and juvenile polychaete tests statistically significant from reference7 if tested, will the water column larval guideline (0 01 d LC ) be exceeded after d hours of mixing if tested, are tissue guidelines exceeded in adult clam bioaccumulation? YES YES YES YES SECTION 401 WATER QUALITY REVIEW YES YES YES MATERIAL IS SUITABLE FOR UNCONFINED, OPEN-WATER DISPOSAL PER SECTION 404 MATERIAL IS NOT SUITABLE FOR UNCONFINED, OPEN-WATER DISPOSAL ~ MATERIAL IS SUITABLE FOR UNCONFINED, OPEN-WATER DISPOSAL Is toxicity in amphipod or juvenile polychaete test >30% over, arid statistically different from, reference? Are there any two of amphipod, luvenile polychaete. sediment larval, and Mlcrotox tests that are statistically significant from reference? tested, are tissue guidelines exceeded in adult clam bioaccumulattan? MATERIAL IS SUITABLE FOR UNCONFINED, OPEN-WATER DISPOSAL PER SECTION 401 The sediment larval test (for Section 401 reviews) is conducted whenever biological testing e required The water column larval test (for Section 404 evaluations) is done only when water column effects are of concern. Microtox lesting is required only for Section 401 reviews it is not required for Section 404 evaluations. The chemical screening level that determines when boaccumulatlon lesting s required 6 higher than for oiher biological testing. Source: PSDDA (1988a) Figure 10. Section 404 and Section 401 disposal guidelines. C744-370S91 74 ------- on statistical comparisons (i.e., "two hit"). A single-hit failure is considered significant if the results from the bioassay are statistically different from the results obtained in the bioassay conducted with a reference sediment and the response is greater than the response noted in the reference bioassay by 30 percent or more (on an absolute basis). A two-hit failure can occur any time the results from two of the bioassays are statistically different from the reference results regardless of the magnitude of the response. Test interpretation for the Section 401 water quality certification includes evaluation of results from the Microtox® bioassay and the three bioassays used in the Section 404(b)(1) evalu- ation. In the case of the amphipod toxicity, larval abnormality, and juvenile polychaete toxicity tests, the test interpretation guidelines relative to single-hit and two-hit failures are the same as described for interpretation under Section 404(b)(1). In addition, a single-hit failure can occur if results from the sediment larval test are statistically different from the reference results and greater than the response obtained in the reference bioassay by 30 percent or more (on an absolute basis). A two-hit failure can occur if any two of the four bioassays are statistically different from the reference results regardless of the magnitude of the response. 6.3 WASHINGTON STATE'S SURFACE WATER QUALITY STANDARDS Implementation of Washington State's Surface Water Quality Standards (Chapter 173-201 WAC) is not governed by a decision-making framework such as those that have been developed for other Puget Sound regulatory programs (e.g., Commencement Bay Superfund investigations, PSDDA, Washington State Sediment Management Standards). Nevertheless, the proposed revisions to the Surface Water Quality Standards (Ecology 1991) include guidance on the application of water quality criteria in the regulation of pollutant discharges. Because this issue is closely related to the regulation of pollutant discharges under Section 403, it is discussed briefly below. Prior to 1991, Washington State's Surface Water Quality Standards (Chapter 173-201 WAC) included provision for mixing (or dilution) zones adjacent to or surrounding wastewater discharges. Exceedances of the water quality criteria were allowed within a mixing zone only if the mixing zone was specifically authorized in a valid discharge permit. Although there were official guidelines describing specifications for mixing zone dimensions, they were not incorporated as part of the Surface Water Quality Standards. There was also no guidance provided on where the acute and chronic water quality criteria should be applied. This presented an interpretive problem because, although it was clear that both acute and chronic water quality criteria had to be complied with beyond the mixing zone, the fact that acute criteria were higher than the chronic criteria for the same substances suggested that compliance with both criteria would not be achieved at the same point in space. Rather, in order to comply with the chronic criteria at the boundary of the mixing zone, compliance with the acute criteria would have to be achieved at some point within the mixing zone, thereby allowing for additional mixing and dilution of the effluent before the discharge plume reached the mixing zone boundary. In 1991, Ecology's proposed revisions to the Surface Water Quality Standards (Ecology 1991) include specifications for maximum mixing zone dimensions in various water bodies. For 75 ------- municipal and industrial wastewater discharges, Ecology incorporated the following concepts in the provisions for mixing zones: ¦ Mixing zones are not assumed to be a given use of public resources ¦ Mixing zones should initially be as small as feasible and should decrease in size as applicable technology evolves ¦ Mixing zones should only be granted when it is demonstrated that there is an overriding public benefit to allowing this use of a public resource. In revising the guidelines for specifying appropriately sized mixing zones, consideration was given to allowing mixing zone dimensions to be defined on the basis of dilution models, rather than using arbitrary, fixed dimensions for various types of discharges. However, in part because of the intensive data requirements for these models, consideration of the use of dilution models for this purpose was abandoned. The proposed revisions to the Surface Water Quality Standards (Ecology 1991) would allow mixing zones within Puget Sound to extend to a maximum horizontal distance from any discharge port of 200 feet plus the water depth. In addition, the mixing zone must not occupy greater than 25 percent of the cross-sectional width of the water body. The proposed revisions to the Surface Water Quality Standards (Ecology 1991) also would include specific requirements for the point of compliance with acute and chronic water quality criteria. As before, chronic criteria would have to be complied with at the boundary of the mixing zone. However, an area smaller than the mixing zone within which the acute criteria could be exceeded would only be allowed if it can be demonstrated that allowance of such a zone will not create a barrier to the migration or translocation of indigenous organisms to a degree that has the potential to cause damage to the ecosystem. The point of compliance with the acute criteria would have to be as close to the point of discharge as practically attainable, but in no case greater than the most restrictive of the following: ¦ Ten percent of the distance from the edge of the outfall structure to the farthest horizontal edge of an authorized mixing zone, as applied in any spatial direction. ¦ Fifty times the discharge length scale in any spatial direction from each discharge port [the discharge length scale is the square root of the cross-sectional area of any discharge port]. In the case of multiport diffusers, this requirement would have to be met for each port using the appropriate discharge length scale of that port. ¦ Five times the local water depth in any horizontal direction from any discharge port. These alternatives for the point of compliance with acute criteria are those recommended by EPA in the Technical Support Document for Water Quality-Based Toxics Control (U.S. EPA 1991d). 76 ------- 6.4 WASHINGTON STATE'S SEDIMENT MANAGEMENT STANDARDS Over the last several years, Ecology has developed regulatory standards and decision- making frameworks to identify and manage contaminated sediments and to perform the sediment-related source control and cleanup activities authorized by Washington State's Water Pollution Control Act and MTCA. The final Sediment Management Standards, promulgated in 1991 (Chapter 173-204 WAC), address three main issues: 1) sediment quality standards, 2) sediment source control standards, and 3) sediment cleanup standards. The decision-making frameworks for each of these are described in the following sections. Additional details are provided in two draft guidance documents (PTI 1991a,b). 6.4.1 Sediment Quality Standards The first component of the Sediment Management Standards establishes sediment quality standards (SQS) based on 1) numerical sediment quality criteria for 47 individual chemicals or groups of chemicals and 2) biological test criteria (PTI 1991a). These standards correspond to the long-term goals for sediment quality in Washington State waters (i.e., no adverse acute or chronic effects on indigenous populations and no significant human health risks). The SQS may be revised in the future as new data become available regarding the toxicity of sediment contaminants to biological resources or risks posed to human health. The numerical sediment quality criteria of the SQS are based on a biological effects-based approach that uses the lowest AET values of four biological indicators (Section 3.1.1) for all chemicals except phenanthrene, whose criterion is based on the EP approach (Read et al. 1989). AET values are based on statistical relationships of chemical and biological variables and do not provide proof of cause-effect relationships for individual chemicals. Therefore, one important feature of the procedures for identifying contaminated sediments is the allowance for the use of direct biological testing to confirm or override the results of direct comparisons of sediment contaminant concentrations with the numerical sediment quality criteria. The analysis of sediment quality is thus conducted in a two-tiered approach. The first tier requires an initial designation of the sediments based on the results of chemical analyses. If the sediment contaminant concentrations do not exceed the numerical sediment quality criteria, the sediment is designated as not having adverse effects on biological resources or posing a significant threat to human health. However, if one or more sediment contaminant concentrations exceed the numerical sediment quality criteria, the sediment is designated as having adverse effects on biological resources or posing a significant threat to human health. At the discretion of Ecology or another interested party, a sediment that either passes or fails the initial designation based on chemical criteria alone may be subjected to confirmatory designation in the second tier, which consists of a suite of biological tests. The sediment must be evaluated using two acute biological tests and one chronic biological test selected from the following list: 77 ------- ¦ Acute biological tests Amphipod mortality test Bivalve (Pacific oyster or edible mussel) or echinoderm (sea urchin or sand dollar) larval abnormality test ¦ Chronic biological tests Benthic macroinvertebrate abundance assessment Juvenile polychaete biomass test Microtox® bioluminescence test. Details on these biological tests are provided in Section 3.1.2. The sediment is determined to have an adverse effect on biological resources when any one of the biological tests demonstrates the results listed in the SQS column of Table 4. 6.4.2 Sediment Source Control Standards The second component of the Sediment Management Standards establishes sediment source control standards for managing sediment contamination that results from ongoing wastewater discharges (PTI 1991a). The sediment source control standards specifically address the following aspects of the process: ¦ Mechanisms for verifying that ongoing discharges with the potential to impact receiving sediments have received all known, available, and reasonable methods of treatment (AKART) prior to discharge, and/or the application of best manage- ment practices (BMPs) as appropriate ¦ Monitoring procedures for evaluating the potential for a discharge to impact receiving sediments ¦ Procedures for determining whether a discharge is eligible for authorization of a sediment impact zone (SIZ), which is analogous to a mixing zone in the water column and would allow contamination in the sediments in the immediate vicinity of the discharge to exceed the SQS ¦ Methods for determining appropriate restrictions (e.g., on size or level of sediment contamination) if an SIZ is to be authorized ¦ SIZ maintenance and closure requirements. The process for evaluating the need for an SIZ is outlined in Figure 11. As a condition of a discharge authorization, all discharges are required to be operating with AKART and/or BMPs in place, or to be on a compliance schedule to meet these requirements. This issue is addressed during the discharge permitting process, regardless of the potential for the discharge to cause an impact to receiving sediments. However, to determine whether a new discharge or one not 78 ------- TABLE 4. BIOLOGICAL EFFECTS CRITERIA FOR PUGET SOUND MARINE SEDIMENTS Biological Test SQSa SIZ Maximum Biological Effects Criteria Amphipod Larval ¦vi u> Benthic macroinver- tebrate Juvenile polychaete Microtox® The test sediment has a significantly higher (Mest, P:£0.05) mean mortality than the reference sediment, and the test sediment mean mortality exceeds 25 percent, on an absolute basis The test sediment has a mean survivorship of normal larvae that is significantly less (/-test, Pi0.05) than the mean nor- mal survivorship in the reference sediment, and the combined abnormality and mortality in the test sediment is more than 15 percent greater, on an absolute basis, than the reference sediment The test sediment has less than 50 percent of the reference area sediment's mean abundance of any one of the following major taxa: Crustacea, Mollusca, or Polychaeta, and the test sediment abundance is significantly different (Mest, P^O.05) from the reference sediment abundance The mean biomass of polychaetes in the test sediment is less than 70 percent of the mean biomass of the polychaetes in the reference sediment, and the test sediment biomass is significantly different (Mest, P^0.05) from the reference sediment biomass The mean light output of the highest concentration of the test sediment is less than 80 percent of the mean light output of the reference sediment, and the two means are signifi- cantly different (Mest, Ps0.05) The test sediment has a significantly higher (Mest, Pi0.05) mean mortality than the reference sediment, and the test sediment mean mortality is more than 30 percent greater, on an absolute basis, than the reference sediment mean mortal- ity The test sediment has a mean survivorship of normal larvae that is significantly less (f-test, />^0.05) than the mean nor- mal survivorship in the reference sediment, and the combined abnormality and mortality in the test sediment is more than 30 percent greater, on an absolute basis, than that in the reference sediment The test sediment has less than 50 percent of the reference area sediment's mean abundance of any one of the following major taxa: Crustacea, Mollusca, or Polychaeta, and the test sediment abundance is significantly different (Mest, /3^0.05) from the reference sediment abundances The mean biomass of polychaetes in the test sediment is less than 50 percent of the mean biomass of the polychaetes in the reference sediment, and the test sediment biomass is sig- nificantly different (Mest, Pi0.05) from the reference sedi- ment biomass Not applicable a SQS - sediment quality standards. The sediment quality standards are failed if one test fails the listed criteria [WAC 173-204-320(3)]. b SIZ - sediment impact zone. The maximum biological effects level allowed within a SIZ is exceeded if one test fails the listed SIZ maximum biological effects criteria [WAC 173-204-420(3)] or if two tests fail the SQS criteria [WAC 173-204-320(3)]. Source: PTI (1991a) ------- ASSESS POTENTIAL FOR SEDIMENT IMPACT • Facility type • Known contaminants • Handling practices • Simple screening tools Assemble existing information or collect new data CONDUCT BASELINE MONITORING • Evaluate status of all known, available, and reasonable methods of treatment (AKART)/ best management practices (BMPs) and initiate compliance schedule if appropriate ASSESS STATUS OF SOURCE CONTROL Permit* • No Sediment Ifnpact Zone (SIZ) • Low-level monitoring • Heopener clause Run generalized model Permit * • No SIZ • Low-level monitoring • Reopener clause Run detailed model ~ Permit* (3 Options) ® © @ • No SIZ • SIZ • No SIZ • Require >AKART • High-level/ • Low-level • High-level moderate-level monitoring monitoring monitoring • Reopener clause • Reopener clause • Reopener clause ~ Permit* (2 Options) CD ® • SIZ • No SIZ • High-level • Low-level monitoring monitoring • Reopener clause * Reopener clause A compliance schedule would be included in the permit for any facility not using AKART or BMPs. Source: PTI (1991a) Figure 11. Process for evaluating the need for sediment impact zones. Likelihood of problem? no Clear source demonstration Sediment Quality Standards yss (SQS) exceedance ^ Exceed SQS in 10 years no yes i Other sources yes yes Exceed SIZ ma 10 years? Total maximum daily load (TMDL) assessment C744-37 0991 80 ------- yet operating with AKART/BMPs in place will adversely impact receiving sediments and therefore be considered for authorization of an SIZ, AKART/BMPs must be identified and used in an initial screening evaluation to estimate wastewater characteristics achievable with appropriate levels of treatment. This initial screening evaluation employs 1) information on facility type, known contaminants, and handling practices; 2) baseline monitoring data (if available); and 3) relatively simple screening tools, such as comparisons of measured or estimated contaminant concentrations on the wastewater particulate fraction (see Section 3.2.3) directly with the numerical sediment quality criteria. If the initial screening evaluation indicates a potential for a discharge operating with AKART/BMPs in place to impact receiving sediments, the next step is to run the sediment impact zone model (see Section 4.1.1) using readily available information. The purpose of this generalized model run is to evaluate whether the discharge has the potential to cause an exceedance of the numerical sediment quality criteria of the SQS within a 10-year period from the date of Ecology's evaluation of the ongoing discharge or the starting date of the proposed discharge, whichever is later. The results of this generalized model run and application of Ecology's best professional judgment provide the basis for predicting the potential for a discharge to result in sediment impacts, and thereby be considered for authorization of an SIZ. Although eligible discharges may be allowed to cause receiving sediments to exceed the SQS within an authorized SIZ, the sediment source control standards also establish specific chemical and biological criteria that define the maximum level of contamination over the SQS that will be allowed within an authorized SIZ. These criteria are referred to as the sediment impact zone maximum criteria, or SIZmax. The SIZmax numerical chemical criteria were set at the second lowest AET value of four biological indicators, and are thus generally at higher concentrations than the numerical sediment quality criteria of the SQS (except when the lowest two AET values are the same). The SIZ^ biological criteria (Table 4) are less stringent than those employed in confirmatory testing for the SQS, and therefore allow for some minor adverse effects within an authorized SIZ. After determining that a discharge is likely to cause an impact to receiving sediments in the initial screening evaluation, detailed model simulations are then conducted using site-specific information (see Section 4.1.1). The primary purpose of this second model run is to evaluate the potential for the discharge to exceed the SIZmax chemical criteria within a 10-year period. In addition to the modeling results, monitoring data may be used to evaluate the potential for a discharge to cause an exceedance of the SIZmax chemical criteria. A secondary purpose of this model run is to determine SIZ specifications (e.g., spatial dimensions of the area exceeding the numerical sediment quality criteria of the SQS). The results of the detailed sediment impact zone model run (or evaluation of monitoring data) may be used to support the following outcomes regarding the need for an SIZ (Figure 11): ¦ If there are no other local sources of the sediment contaminant(s): No SIZ will generally be authorized if one or more sediment contami- nant concentrations exceed the SIZmax chemical criteria 81 ------- An SIZ may be authorized if one or more sediment contaminant concen- trations exceed the numerical sediment quality criteria of the SQS, but not the SIZmax chemical criteria No SIZ will be authorized if there are no exceedances of the numerical sediment quality criteria of the SQS a If there are other local sources of the sediment contaminant(s): An SIZ may be authorized if one or more sediment contaminant concen- trations exceed the numerical sediment quality criteria of the SQS, but not the SIZmax chemical criteria No SIZ will be authorized if there are no exceedances of the numerical sediment quality criteria of the SQS No SIZ will generally be authorized if one or more sediment contami- nant concentrations exceed the SIZmax chemical criteria, and an evalu- ation of the TMDL will have to be initiated, potentially resulting in WLA among the various contaminant sources. In cases where an SIZ will be authorized in a discharge permit, the permit will specify appropriate monitoring requirements to ensure that the modeling predictions are realized, and that exceedances of the SIZmax chemical (and possibly biological) criteria do not occur. Sediments with contamination above SIZmax that fall outside of authorized SIZs would become a cleanup site subject to the sediment cleanup standards (see Section 6.4.3). 6.4.3 Sediment Cleanup Standards The third component of the Sediment Management Standards establishes a decision process for identifying contaminated sediment areas and determining appropriate cleanup responses (PTI 1991b). This process, known as the sediment cleanup decision process, includes screening and ranking procedures designed to focus limited resources on areas of sufficient concern to warrant consideration of active cleanup. SEDRANK, a scoring procedure evaluating ecological and human health hazards, will be used as a tool in the ranking of contaminated sediment areas (PTI 1991c). The sediment cleanup decision process includes procedures for selecting an appropriate cleanup alternative (e.g., dredging or capping) and cleanup standards (i.e., the level of contamination that will be allowed to remain in place following cleanup) on a site-specific basis. Natural recovery is recognized as a viable response option for sediments that are expected to recover unaided within a 10-year time frame. Because the purpose of the sediment cleanup decision process is markedly different from that of the Section 403 program, and because the decision-making framework for this process is complex, it is not discussed in this report. Instead, several relevant aspects of the sediment cleanup standards are briefly discussed in the remainder of this section. Additional details on the sediment cleanup decision process are provided in a draft guidance document (PTI 1991b). 82 ------- The sediment cleanup standards provide chemical and biological criteria (the cleanup screening level or CSL) used to define a level of contamination above the SQS that will trigger consideration of the need for site cleanup. The sediment cleanup standards also provide chemical and biological criteria (the minimum cleanup level or MCUL) used to define the maximum level of contamination that will be allowed to remain in the sediments once cleanup is complete. The sediment cleanup standard that will be required to be met following cleanup at individual sites will be established on a site-specific basis and may range between the SQS and the MCUL. The site-specific sediment cleanup standards are intended to be as close as practicable to the SQS, with consideration of net environmental effect, cost, and technical feasibility of any cleanup action. Evaluation of natural recovery of contaminated sediments is also an important part of the determination of site-specific sediment cleanup standards. The sediment cleanup standards include provisions for authorization of sediment recovery zones, which are areas where sediments containing contaminants above the SQS are left in place as part of the cleanup action decision for a site. The intent of such authorizations of sediment recovery zones is to achieve natural recovery to the SQS within 10 years, although the authorization may extend for longer periods if cleanup of the site is not practicable. Further information on the use of contaminant transport and fate models in defining a sediment recovery zone is provided in Section 4.1.2. Recognizing that there should be consistency in the maximum sediment contamination that will be allowed to remain in the environment following the implementation of source control measures and the completion of cleanup at contaminated sediment sites, the same chemical concentrations and biological effects levels were established for the SIZ^, the CSL, and the MCUL. These standards were established at chemical concentrations or biological effects levels (see Table 4 for the SIZmax biological criteria, which are the same as the biological criteria for the CSL and MCUL) that are equal to or higher than the SQS. The chemical concentrations and biological test criteria for the SQS, SIZmax, CSL, and MCUL apply only to marine sediments in Puget Sound. Similar criteria for freshwater and low salinity sediments are currently reserved and will be addressed by Ecology on a case-by-case basis. The Sediment Management Standards were also formulated to be generally consistent and compatible with PSDDA. Consistency was established by setting the SIZ^, CSL, and MCUL at chemical concentrations and biological effects levels that are as similar as possible to the PSDDA guidelines for unconfined, open-water disposal of contaminated sediments. Exact correspondence was not obtained because slightly different sets of biological tests and test interpretation guidelines are used for the two programs. 6.5 PUGET SOUND ESTUARY PROGRAM The PSEP Urban Bay Action Program provides a focus for compiling environmental quality data, controlling specific contaminant sources, and improving water and sediment quality conditions in a number of the urbanized embayments of Puget Sound (PTI 1990). As a result of the prioritization of contaminant sources developed in an urban bay action program for a specific embayment, inspections are conducted, appropriate BMPs are identified for dischargers, permits are issued to unpermitted sources, and additional limitations are placed on existing 83 ------- permitted discharges upon permit renewal. The priorities for contaminant source control activities are based on information collected in an initial data compilation and problem identification phase. The decision-making framework of the PSEP Urban Bay Action Program was developed from the decision-making framework used in the Commencement Bay Superfund investigations (see Section 6.1). It relied on the same preponderance-of-evidence approach and a similar suite of environmental indicators. The only two major differences were that 1) the Microtox® bioluminescence test was added to the suite of toxicity tests applied in Commencement Bay and 2) the EAR approach was extended to use in water quality assessment, whereas in Commence- ment Bay its use was limited to sediment quality and biological effects assessments. Whereas the Commencement Bay investigations were designed to satisfy the requirements of CERCLA, the Urban Bay Action Program was designed to address control of contaminant releases through other federal, state, and local regulatory authorities (PTI 1990). The general decision-making framework could be applied to either a small data set derived from previous studies or a comprehensive data set collected as part of the Urban Bay Action Program. A series of data collection activities was typically implemented in a tiered fashion to correspond with increased funding or information over time. For example, Tier 1 might consist of a shoreline reconnaissance survey of potential sources and an initial source evaluation; Tier 2 might involve meeting with industries to discuss efficient industrial management practices and additional data needs for source prioritization; Tier 3 might involve inspections of industrial facilities for compliance with toxic substance regulations and an evaluation of potential sources of contaminants; and Tier 4 might involve more extensive field sampling and the detailed evaluation of environmental data as in Commencement Bay (see Section 6.1). The Tier 4 evaluation assumes that environmental degradation must be assessed for areas within an urban bay to determine priorities for source evaluations and remedial actions. This approach is most appropriate when few data on contaminant sources are available and sources cannot be easily prioritized based on other information (e.g., information on land use and industrial processes). The Tier 4 evaluation may also be warranted when a demonstration of environmental harm is required to proceed with enforcement action or to elicit actions from responsible parties. Responsible parties could either be legally forced to conduct further sampling and analysis or to initiate immediate source control. In some cases, environmental data might not be needed to prioritize contaminant sources and to implement source controls (e.g., where the most important sources of contaminants are obvious and data on these sources are sufficient for regulatory controls). 6.6 WASHINGTON STATE'S MODEL TOXICS CONTROL ACT Implementation of Washington State's MTCA is not governed by a decision-making framework that is relevant to Section 403 because the law is primarily oriented toward the cleanup of terrestrial hazardous waste sites, while MTCA references the sediment cleanup standards of the Sediment Management Standards (see Section 6.4) for the cleanup of aquatic hazardous waste sites with contaminated sediments. However, one aspect of the MTCA Cleanup Regulation (Chapter 173-340 WAC) that is related to Section 403 is the selection of cleanup 84 ------- levels that would be applied at sites that involve the release of hazardous substances to surface waters. The MTCA Cleanup Regulation provides three approaches (Methods A, B, and C) for deriving concentrations of hazardous substances in surface water (i.e., surface water cleanup levels) that are determined to be protective of human health and the environment under specified exposure conditions. Method A is used to determine cleanup levels at sites requiring routine cleanup actions or at sites that have relatively few hazardous contaminants. Surface water cleanup levels under Method A are required to be at least as stringent as criteria published in the Surface Water Quality Standards (Chapter 173-201 WAC) and federal water quality criteria derived for the protection of aquatic life (U.S. EPA 1986). Where chemical criteria are not defined by existing regulations, cleanup levels are equivalent to the natural background concentration, defined as "the concentration of a hazardous substance consistently present in the environment which has not been influenced by localized human activities." Method B is the standard method for determining cleanup levels for surface water and other environmental media. As in Method A, Method B cleanup levels must be at least as stringent as federal or state water quality criteria, when available. Method B has the additional requirement that human health risk-based algorithms should be used to calculate contaminant concentrations in surface water that will not lead to bioconcentration of aquatic contaminants and consequent human health risks from the consumption of contaminated fish and shellfish (see Section 3.2.4 for a discussion of the use of these algorithms). The algorithms are provided to derive cleanup levels for hazardous substances for which human health risk-based water quality criteria are not available or are not considered to be sufficiently protective. Method C is provided for situations in which compliance with cleanup levels developed under Method A or Method B is impossible to achieve (e.g., because standards are based on theoretical models or dilution series and are below instrumental detection limits) or may cause greater environmental harm than leaving the contaminants in place (e.g., through physical habitat disturbance). Method C uses the same algorithms provided for Method B (with less conservative exposure assumptions) to derive surface water cleanup levels. For example, where Method B calculations are based on the assumption that 50 percent of the fish consumed by an exposed person comes from the contaminated waters, Method C calculations are based on the assumption that 20 percent of the total fish consumed comes from the contaminated waters. In addition, risks up to 1 x 10"5 are allowed under Method C. These differences may result in higher surface water cleanup levels than those calculated using Method B. However, all state and federal water quality standards must still be met. The cleanup levels selected for a given site will be the most stringent of the levels either available in applicable state and federal laws derived by one of these three methods. MTCA includes provisions allowing Ecology to establish cleanup levels that are even more stringent than those derived using any of the above methods if evaluation of site-specific information and the judgment of Ecology indicate that more stringent criteria are necessary to protect human health and the environment. EPA water quality criteria for the protection of aquatic organisms have been used as cleanup standards at hazardous waste sites, but they were not developed for that purpose. Ecology is 85 ------- deriving cleanup levels under MTCA that are based on integration of several types of ecological impact data and are explicitly protective of ecological receptors. A proposed approach is currently under review by Ecology's Ecological Advisory Subcommittee (PTI, in preparation). The approach is a tiered hazard assessment that combines chemical water quality criteria derived by U.S. EPA (1986), results of toxicity tests conducted on laboratory-raised organisms using site water, and analysis of indigenous aquatic communities. The integrated approach is consistent with guidelines provided in EPA's Technical Support Document for Water Quality-Based Toxics Control (U.S. EPA 1991d) and the policy objectives described in that document. 86 ------- 7. APPLICABILITY OF PUGET SOUND APPROACHES TO SECTION 403 As described in Section 1, the current Section 403 regulations require a determination that a point-source discharge will not cause unreasonable degradation of the marine environment. A determination of no unreasonable degradation can be made through the use of 10 ocean discharge criteria which are specified in the regulations (Table 1). Such determinations require a substantial amount of site-specific data, because consideration must be given to a multitude of potential effects of the discharge on the receiving environment. In the absence of sufficient data to make such a determination, a Section 403 permit can still be issued subject to additional conditions, as long as it can be determined that the permitted discharge will not cause irreparable harm to the marine environment. For Section 403 permits issued on the basis of a determination of no irreparable harm, additional monitoring will be required under the permit so that the determination of no unreasonable degradation can be made at some time in the future. Currently, a relatively small number of ocean dischargers are likely to have sufficient site- specific information to make determinations of no unreasonable degradation (U.S. EPA 1990). Consequently, many of the Section 403 permits that will be issued over the next several years will likely be issued under the no irreparable harm provisions of Section 403. During this period, EPA will be developing further technical guidance on appropriate approaches to the determination of no unreasonable degradation. Thereafter, data collected in monitoring programs will be used to make these determinations. In the interim, however, there is a more immediate need for technical approaches that can be applied to determinations of no irreparable harm. In this section, technical approaches currently being applied in Puget Sound will be evaluated for their applicability to both kinds of determinations. 7.1 COMMON ELEMENTS OF THE PUGET SOUND REGULATORY PROGRAMS Before evaluating the potential applicability of the Puget Sound technical approaches to Section 403, it is important to summarize the common elements of these approaches in assessing impacts on the receiving environment and in managing pollutant releases to the environment. In recent years, Puget Sound regulatory programs concerned with such diverse subjects as the management of point-source discharges, the disposal of dredged material, and the cleanup of contaminated sediments have addressed these issues from an effects-based approach. This commonality of approach is a result of the recognition of the limitations of the former focus on technology-based control of wastewater discharges, and of the prominent role played by toxic pollutants in causing many of the observed environmental impacts. There have been parallel improvements in methods of controlling environmental impacts mediated by both water and sediment contaminated with toxic pollutants. Improvements in the ability to control water pollution in Puget Sound have mirrored those being adopted in other 87 ------- states and have included increased use of water quality criteria for toxic pollutants, increased use of whole-effluent toxicity tests, and the specification of discharge limits from a water quality- based approach. Even greater improvements have been made in the ability to assess and to begin to control the effects of contaminated sediments in Puget Sound. In April 1991, Washing- ton became the first state to adopt Sediment Management Standards (Chapter 173-204 WAC) that included numerical criteria for assessing sediment quality. The recent focus on sediment contamination stems in large part from the realization that many of the most toxic and persistent pollutants in the marine environment have an affinity for binding to particulate matter; consequently, these pollutants accumulate in the sediments in areas near the sources of these materials. The following premises form the cornerstones around which the decision-making frame- works in each of the major Puget Sound regulatory programs have been developed: ¦ Decisions are generally made on the basis of a preponderance of evidence (i.e., multiple indicators such as analyses of sediment and water chemistry, water and sediment toxicity tests, and assessments of naturally occurring communities of organisms are used, and greater attention is generally focused on areas or situations when more than one indicator exhibits a significant problem). ¦ Evaluation procedures are typically tiered, with chemical criteria serving as the first tier, progressing to biological criteria in the higher tiers. Along a continuum of increasing sediment contamination, there is a common acknowledgment of two "break points." Below a threshold value, the effects of sediment contamination are considered to be insignificant; above a higher concentration threshold, the effects of sediment contamination are likely to be so severe that some form of control or remediation will probably be required. Between these two sediment contaminant concentrations, some form of biological testing is generally required to demonstrate the presence or absence of significant effects. ¦ Some minor adverse effects on the receiving environment are considered accep- table for most activities (e.g., point-source discharges and dredged material disposal), provided such effects are reasonably limited in spatial extent, are either temporary or potentially reversible, and are of insufficient severity to be con- sidered major adverse effects. ¦ Decisions regarding either the need for restricting the release of contaminants to the environment through discharge limitations or the need for cleanup of historical contamination are made with allowance for natural recovery as one element of contaminant control. ¦ Although the decision-making frameworks provide guidance to assist decision- makers, there is always allowance for the use of best professional judgment in reaching appropriate decisions. Each of these premises is potentially applicable to the decision-making framework that will be developed for the Section 403 program. 88 ------- In addition to these major premises, there are other elements of the Puget Sound technical approaches common to two or more of the major regulatory programs. In the Commencement Bay Superfund investigations and in the Washington State Sediment Management Standards, there is a common recognition that there are likely to be cases where insufficient site-specific information currently exists to make a determination of adverse effects. In both of these programs, there are provisions for basing current decisions on the results of modeling future conditions, subject to confirmation through further monitoring. Even in such situations, the magnitude of the required monitoring is likely to be tiered (i.e., monitoring requirements would increase with the perceived likelihood of adverse effects). Finally, the development of technical approaches to assessing the environmental effects of water and sediment contamination in Puget Sound has not been limited to assessment of ecological impacts. Both the Commencement Bay Superfund investigations and PSDDA have developed methods for assessing, and thereby beginning to manage, the human health risks associated with sediment contamination by toxic pollutants. In the former case, this led to the development of a numerical sediment quality criterion for PCBs that was designed to be protective of human health potentially at risk through consumption of contaminated seafood organisms. In the latter case, this led to the imposition of a requirement for a bioaccumulation bioassay when dredged materials proposed for unconfined, open-water disposal had high levels of contamination of one or more pollutants that could bioaccumulate in resident organisms. Similarly, under MTCA, a method was developed for establishing site-specific surface water cleanup criteria that were to be protective of human health potentially at risk through consump- tion of contaminated seafood organisms. 7.2 APPLICATIONS OF PUGET SOUND APPROACHES TO SECTION 403 DETERMINATIONS In evaluating the applicability of the technical approaches currently employed in Puget Sound to the needs of the Section 403 program, the distinction between the determinations of no irreparable harm and no unreasonable degradation is important. In the near future, most of the Section 403 permits will be issued or reissued on the basis of determinations of no irreparable harm. Such determinations, typically made in the absence of large amounts of site- specific information, have in the past relied heavily on the best professional judgment of the staff in the permitting agencies (i.e., EPA regional offices or delegated state agencies). However, to the extent possible, it is desirable for EPA to explore sound technical approaches that can be consistently applied throughout the country in making the determinations of no irreparable harm. Such technical approaches will, of necessity, rely on information readily available from any existing monitoring program (e.g., required effluent monitoring results), literature reviews, or short-term data collection efforts required of the dischargers (e.g., one-time monitoring of certain receiving environment conditions). Certain technical approaches that have been applied in the Puget Sound regulatory programs could be adapted for such uses under Section 403, and these are discussed in Section 7.2.1. In a smaller number of cases where existing site-specific information is much more extensive, Section 403 permits will be issued or reissued following a determination of no unreasonable degradation. Many more such determinations can be expected to be made in the 89 ------- future as permits initially issued or reissued on the basis of determinations of no irreparable harm come up for renewal, and more extensive site-specific information will then be available from monitoring required under the permit. The complexity of these determinations is expected to be much greater than the determinations of no irreparable harm, and consequently they will require the development of much more detailed technical guidance and decision-making frameworks. Certain technical approaches that have been applied in the Puget Sound regulatory programs also show considerable promise for application to determinations of no unreasonable degradation, and these are discussed in Section 7.2.2. 7.2.1 Determinations of No Irreparable Harm Under the provisions of 40 CFR 125.123(c), discharge permits may be issued in the absence of sufficient information to make a determination of no unreasonable degradation, provided that: ¦ Such discharge will not cause irreparable harm to the marine environment during the period in which monitoring is undertaken. ¦ There are no reasonable alternatives to the onsite disposal of these materials. ¦ The discharge will be in compliance with all permit conditions established pursuant to 40 CFR 125.123(d). Such permit conditions include compliance with the Ocean Dumping Criteria of 40 CFR 227.27 (which address limiting permis- sible concentrations of liquid, suspended particulate, and solid phases of the discharge established on the basis of toxicity tests), requirements for monitoring to be conducted under the Section 403 permit, inclusion of a reopener clause, and certain other conditions. Technical approaches that have been employed in Puget Sound are potentially applicable to determinations of no irreparable harm and to evaluations of compliance with the Ocean Dumping Criteria. They are not likely applicable to evaluation of alternatives to onsite disposal. There are also direct parallels between the monitoring required under several of the Puget Sound regulatory programs and the monitoring to be required under these permits. Before discussing the technical approaches, it is important to consider the meaning of "irreparable harm" in the context of the Section 403 regulations. Short of causing the extinction of a species, there are likely few, if any, impacts of wastewater discharges in the marine environment that could truly be considered "irreparable" given sufficient recovery time. However, "irreparable" could be understood to mean "irreparable within a reasonable period of time." While such a reasonable period of time is not defined by the regulations, it should be noted that two Puget Sound regulatory programs have adopted 10 years as being a reasonable period to expect recovery to have occurred. In the Commencement Bay Superfund investi- gations, areas with sediment contamination that could be expected to recover naturally through processes of sedimentation and biodegradation, and thereby achieve acceptable sediment contaminant concentrations within 10 years, were not considered to require active sediment remediation (see Section 6.1.3). Similarly, the Washington State Sediment Management Standards (Chapter 173-204 WAC) allow for a period of 10 years within which sediment contaminant concentrations inside authorized sediment impact zones must meet acceptable levels, 90 ------- and a period of 10 years for the natural recovery of sediment contamination within sediment recovery zones (see Section 6.4). A similar period may be considered appropriate for expecting recovery of the receiving environment in the vicinity of a Section 403 discharge permitted under the no irreparable harm provisions. The Section 403 regulations are unclear on the precise meaning of "harm," defining it only as "significant undesirable effects." Harm is herein understood to mean any of the same types of environmental effects that would constitute unreasonable degradation, although the degree of degradation is undefined. It is interesting to note that the major Puget Sound regulatory programs have a common understanding that some minor adverse effects are allowable in most situations (see Section 7.1), at least on a temporary basis, and that it is not realistic to expect all of Puget Sound to achieve pristine conditions. To be considered indicative of adverse effects, biological indicators of sediment contamination must demonstrate statistically significant departures from reference conditions and minimum response levels (e.g., increases in toxic response in sediment bioassays and depressions in benthic macroinvertebrate abundances) (see Sections 3.1.1 and 3.1.2). With regard to the interpretation of "irreparable harm," it is also important to consider the types of receiving environment impacts that are likely to continue to occur long after the cessation or modification of a discharge. Effects within the water column are largely transitory, and therefore evidence of irreparable harm should more appropriately be sought in the sediments (or potentially in long-lived organisms), because these are the reposi- tories for discharge-related contamination that may last long after the cessation or modification of the discharge. Because of public sensitivity, significant human health risks associated with a discharge may also be considered irreparable harm, regardless of their duration. Determinations of no irreparable harm must be made with a minimum of site-specific data. Within the Puget Sound regulatory programs, several screening-level analyses are applied to such situations where decisions must nevertheless be made on permitting or other regulatory issues. In situations where information may be available on contaminant concentrations associated with wastewater particulate material (see Section 3.2.3), direct comparison of these concentrations with available sediment quality criteria may provide a relatively simple indication of whether the wastewater discharge has the potential to result in unacceptable impacts. Under the Washington State Sediment Management Standards (Chapter 173-204 WAC), the sediment impact zone model can be run in a generalized mode with only a minimum of site-specific data to determine whether there is a likelihood for a wastewater discharge to adversely affect the sediments in the vicinity of the discharge (see Section 6.4). In such generalized model runs, the key site-specific data are the concentrations of contaminants and particulate material in the wastewater. In lieu of site-specific data on conditions in the receiving environment, conservative estimates of these variables can be used for input to the model. The model output is evaluated to determine whether the discharge has the potential to exceed available sediment quality criteria. As additional site-specific data become available, the model can be applied in a more detailed manner to improve the reliability of its predictions. Preliminary ecological risk assessment models, such as that used for the Harbor Island Superfund site (see Section 4.3.1), can also be applied with a minimum of site-specific information. Assuming that the identities of contaminants in the wastewater are known, qualitative information on ecological receptors and pathways of contaminant transfer in the general area can be used in a hazard-ranking approach to estimate ecological risks associated 91 ------- with the discharge. While contaminant concentrations in various media can be used as one of the decision criteria in this approach, their use is not mandatory. Given the typical costs associated with the analysis of contaminant concentrations in various media, the approach shows promise of being a cost-effective screening tool for qualitatively evaluating ecological risks without the need for extensive analytical data. In the absence of human health-based sediment quality criteria, it is possible to "back- calculate" sediment contaminant concentrations that would be protective of human health potentially at risk through consumption of contaminated seafood organisms by the method applied in the Commencement Bay Superfund investigations (see Section 4.2.1). The sediment concentrations of potentially toxic contaminants estimated by this method could be compared with either actual sediment contaminant concentrations in the vicinity of the discharge (if available) or sediment contaminant concentrations predicted by the simple modeling applications described above. This approach could then serve as a simple screening-level analysis of the likelihood of a discharge causing unacceptable human health impacts. Refinement in these initial estimates could occur as additional data are collected in the monitoring program. The increased monitoring requirements to be imposed on discharges permitted under the no irreparable harm provision of the Section 403 regulations are similar to those requirements mandated by several of the Puget Sound regulatory programs. In each case, the increased degree of monitoring is designed to provide additional data that will be used in subsequent decision-making. The degree of monitoring to be required will vary with the perceived likelihood of adverse effects, and the results may be used to confirm model predictions that formed the basis for a former regulatory decision. In the Commencement Bay Superfund investigations, for instance, areas with contaminated sediments that are predicted to recover naturally based on modeling results will be monitored periodically to ensure that such recovery does in fact occur (see Section 4.1.2). The expanded monitoring requirements now being included in major NPDES permits being issued in Puget Sound (see Section 5.1) are directly analogous to those to be included in Section 403 permits. These monitoring requirements are primarily oriented toward assessment of impacts in the receiving environment, and the results will be used in more detailed evaluations to be conducted during the next permit review cycle. The Washington State Sediment Management Standards (Chapter 173-204 WAC) also include provisions for increasing the monitoring requirements for discharges with a potential for impacting the sediments. The resulting database can then be used to support subsequent permitting decisions and to confirm the predictions of the sediment impact zone model (see Sections 4.1.1 and 6.4). Although not necessarily directly applicable to Section 403 monitoring programs in other areas of the country, the Puget Sound Protocols (PSEP 1990) could serve as a model for the development of uniform national monitoring guidance under Section 403. The consensus- building process by which the Puget Sound Protocols were developed (see Section 5.2) represents a valuable approach that could also be applied under the Section 403 program. The requirement for demonstrating compliance with the Ocean Dumping Criteria could be satisfied, in part, by employing either the toxicity tests currently being used in Puget Sound regulatory programs (see Section 3.1.2), or closely related toxicity tests using organisms appropriate to other biogeographic regions. EPA Region 10 already applies some of these 92 ------- bioassays for this purpose. The requirement for demonstrating a sufficient reduction in toxicity through dilution may also be met through application of contaminant transport and fate models currently being employed in Puget Sound (see Section 4.1.1). 7.2.2 Determinations of No Unreasonable Degradation Under the provisions of 40 CFR 125.122(a), a determination of no unreasonable degradation of the marine environment is made based on consideration of 10 ocean discharge criteria (Table 1). Sediment and water quality assessment tools, modeling techniques, monitoring guidance, and decision-making frameworks currently employed in the Puget Sound regulatory programs are potentially applicable to evaluations of these types of information. The corres- pondence between the 10 ocean discharge criteria and these aspects of the technical approaches being employed in Puget Sound is shown in Figure 12. This matrix illustrates the broad applicability of the Puget Sound technical approaches to the types of evaluations required under Section 403. For some of the ocean discharge criteria (e.g., consideration of the potential transport and fate of pollutants or the composition and vulnerability of exposed biological communities), technical assessment approaches now being employed in Puget Sound will probably be either directly applicable or applicable with only minor modifications. For other ocean discharge criteria [e.g., consideration of the requirements of a Coastal Zone Management Plan (CZMP)], evaluation procedures may not be amenable to the use of technical approaches recently developed for use in Puget Sound. The remainder of this section describes major areas of correspondence between the Puget Sound technical approaches and the required Section 403 evaluations for determinations of no unreasonable degradation. The preponderance-of-evidence approach to assessing impacts on the receiving environment is perhaps one of the most important aspects of the Puget Sound regulatory programs that should be considered for adoption in any future technical guidance for the Section 403 program. For assessments of impacts associated with toxic pollutants introduced into the marine environment, all of the Puget Sound programs have relied on a combination of indicators (both chemical and biological) that together provide a more integrated assessment of impacts than do approaches based on any single environmental indicator. While the exact combination of indicators has varied among programs, in part because of differences in focus among the programs, their common reliance on the preponderance-of-evidence approach reflects the importance placed on having a multiphased assessment of environmental conditions. A prime example of the preponderance-of-evidence approach is the sediment quality triad, which combines assessments of sediment contamination, sediment toxicity, and benthic macroinvertebrate assemblages to achieve an integrated assessment of sediment quality (see Section 3.1.1). For assessments of sediment contamination, Puget Sound programs have focused on a list of chemicals considered to be of most concern because of their potential toxicity and their distribution in Puget Sound sediments. By focusing on this "short list" of chemicals, attention is not diverted to chemicals considered unlikely to be responsible for most observed effects. For assessments of sediment toxicity, the Puget Sound programs have used a combi- nation of acute and chronic sediment toxicity tests (see Section 3.1.2). Use of these toxicity tests has benefitted from standardized protocols, specified QA/QC procedures, and the requirement that results be statistically different from reference sediment responses to be con- 93 ------- PUGET SOUND TECHNICAL APPROACHES Sediment Quality Assessment Tools Water Quality AseeMmerit Tool* Hodallng Techniques Monitoring Guidance Decision-Making Frameworks SECTION 403 OCEAN DISCHARGE CRfTERIA Sediment Quality Criteria Sediment Bioassays Benthic Macroinvertebrate Assessments Water Quality Criteria Whole-Effluent Toxicity Tests Analysis of Wastewater Particulates Surface Water Cleanup Levels Based on Human Health Contarmnant Transport and Fate Models Human Health Risk Assessment Models Ecological Risk Assessment Models Receiving Environment Monitoring PSEP Protocols Permit Writers Manual Commencement Bay Superfund Investigations Puget Sound Dredged Disposal Analysis Program Washington State Surface Water Quality Standards Washington State Sediment Management Standards Puget Sound Estuary Program Model Toxics Control Act 1. Quantities, composition, and potential for bioaccumulation or persistence of the pollutants to be discharged 2. Potential transport of such pollutants by biological, physical, or chemical processes ¦ ¦ B B B B B fl ¦ 3. Composition and vulnerability of potentially exposed biological communities B B B B B B ¦ B 4. Importance of the receiving water area to the surrounding biological community ¦ n ¦ ¦ B fl B B B B ¦ B 5 Existence of special aquatic sites ¦ B 6. Potential direct and indirect impacts on human health ¦ ¦ ¦ ¦ B B B 7. Existing or potential recreational and commercial fishing B B B 8. Any applicable requirements of an approved Coastal Zone Management Plan 9. Such other factors relating to the effects of the discharge as may be appropriate 10 Manne water quality criteria ¦ ¦ B B B B B B B B Figure 12. Correspondence between Puget Sound technical approaches and Section 403 ocean discharge criteria. ------- sidered as evidence of potential adverse effects. Assessments of benthic macroinvertebrate assemblages provide evidence of in situ effects of chemical toxicity that supplement the results of the sediment bioassays. Puget Sound regulatory programs have focused on assessments of major benthic macroinvertebrate taxa because reductions in the abundances of major taxa are presumed to be more environmentally significant than are reductions in the abundances of individual species. Reductions in the abundances of major taxa may also be attributed to chemical toxicity more readily than can more subtle shifts in species abundances which may be due to factors other than toxicity (see Section 3.1.2). Use of the sediment quality triad should be considered for application to Section 403 evaluations, even though different chemicals of concern or different sediment bioassays from those used in Puget Sound may be more appropri- ate in other areas of the country. The development of empirically derived sediment quality values based on the AET approach has proven invaluable to the Puget Sound regulatory programs and, in modified forms, these values have been incorporated into the decision-making frameworks of several of the programs. The benefits of the AET approach and the reasons for its use in Puget Sound are described in Section 3.1.1. The sediment quality values established by this approach are used in several different ways to establish the "break points" that delimit ranges of sediment contamination which 1) are not likely to have adverse effects, 2) require biological testing to demonstrate adverse effects, or 3) are likely to have adverse effects (see Section 7.1). It is recognized that the AET values developed for Puget Sound may not be readily transferable to other areas of the country because the biological indicators used to establish the AET values may not be applicable to other biogeographic regions. Nevertheless, the AET approach itself could be applied elsewhere, although a relatively large database of synoptically collected sediment chemistry and biological samples would be required to develop AET values for other biogeographic regions of the country. However, even if other methods (e.g., the equilibrium partitioning approach) are used to establish sediment quality values, the desirability of having numerical sediment quality criteria for assessing environmental impacts of wastewater discharges is apparent. Washington State's adoption of EPA's numerical water quality criteria for toxic pollutants as part of the Surface Water Quality Standards (Chapter 173-201 WAC) gave Ecology the authority to regulate the discharge of these toxic pollutants on the basis of maximum con- centration limits in the receiving water (see Section 3.2.1). All other states were also required by the federal Water Quality Act of 1987 to either adopt these criteria as standards or develop their own water quality standards for toxic pollutants. This action, while already accomplished in Washington State, should be followed by other states because the availability of numerical water quality criteria represents a significant improvement over the limited ability to regulate the discharge of toxic pollutants under the narrative statements common to the water quality standards of many states prior to 1987. A related development within Washington State is the proposed revision of the Surface Water Quality Standards (Ecology 1991) that would define the points of compliance with the acute and chronic criteria (see Section 6.3). By defining these points of compliance in accordance with EPA guidance (U.S. EPA 1991d), the state will have effectively increased the ability to regulate discharges on the basis of these criteria. Increased receiving water monitoring requirements (see Section 5.1) may then be targeted to demonstrate compliance with these criteria. 95 ------- The inclusion of requirements for whole-effluent toxicity testing in major discharge permits in the Puget Sound area (see Section 3.2.2) also represents a significant improvement in Washington State's ability to regulate these discharges from an effects-based approach. The required biomonitoring uses standardized EPA protocols for testing whole-effluent toxicity, and the results will be evaluated to determine whether discharge limits need to be established for toxicity, incorporating EPA's TMDL/WLA approach outlined in the Technical Support Document for Water Quality-Based Toxics Control (U.S. EPA 1991d). While Washington State's use of this approach does not represent a new or innovative technique, it serves as an example of one state's attempt to incorporate recent EPA guidance into its discharge permitting process. The expected technical guidance to be developed for the Section 403 program may include similar requirements for investigating whole-effluent toxicity and developing water quality-based discharge limits. The proposed use of data on contaminant concentrations in wastewater particulate material (see Section 3.2.3) will represent a significant development in the state's ability to regulate the discharge of toxic pollutants for two reasons: 1) it permits detection of chemicals present in wastewater that may be undetectable in whole water samples, but that may still be present in the particulate phase at concentrations sufficient to have adverse effects and 2) it provides important information on the pollutants likely to accumulate in the sediments that may be used in screening discharges for their potential to have adverse effects or in modeling the transport and fate of discharged pollutants. Ecology is currently exploring methods for the collection and analysis of particulate material. Once perfected, these methods will greatly improve the ability to collect information on this important fraction of wastewater discharges. Similar use could be made of wastewater particulate data in the evaluation of Section 403 discharges. As discussed in Section 6, several of the major Puget Sound regulatory programs include a framework of evaluation procedures designed to evaluate the effects of point-source discharges or in-place sediment contaminants. The decision-making frameworks for each of these programs are generally predicated on the understanding that not all situations should be evaluated by the same rigorous set of procedures. The varying characteristics of individual situations (e.g., the volume and chemical composition of a point-source discharge, the magnitude and complexity of sediment contamination, and the number and variety of contaminant sources in a given area potentially contributing to a problem) make it imperative that the evaluation procedures be flexible to account for different probabilities of adverse effects. Consequently, the evaluation procedures are typically tiered such that the data requirements and the complexity of the actual evaluations increase as the probability of adverse effects increases. Hence, decisions can be made on relatively simple situations (e.g., issuing an NPDES permit for a small point-source discharger with few toxic contaminants in its effluent, or permitting the disposal of a small volume of dredged material from an uncontaminated site) in the absence of considerable site- specific data and without complex evaluation procedures. For more complex situations (e.g., issuing an NPDES permit for a large point-source discharger with many toxic contaminants in its effluent, or permitting the disposal of a large volume of dredged material from a contam- inated site), more site-specific data and more sophisticated analyses may be required. The decision-making frameworks include screening tools that enable decisions to be made about the appropriate level of effort or quantity of data that will be required. Despite their somewhat formalized structure, there is always allowance within the decision-making frameworks for the exercise of best professional judgment on the part of the decision-makers. 96 ------- While the combined scope of the major Puget Sound regulatory programs is far broader than that of Section 403, the logical structure of the decision-making frameworks is directly analogous to the requirements of the Section 403 program for future technical guidance. The decision- making frameworks progress from simpler, less expensive analyses, to more detailed, costlier analyses. Through use of these decision-making frameworks, each program can focus limited resources on those situations of the greatest environmental significance. Each of these decision- making frameworks makes use of the sediment and water quality assessment tools, the modeling techniques, and the monitoring guidance discussed in Sections 3, 4, and 5, respectively, of this report. Although their goals differ, there are common elements among the regulatory programs. For instance, the Commencement Bay Superfund investigations, PSDDA, the Washington State Sediment Management Standards, and PSEP's Urban Bay Action Program have all relied on sediment quality values developed using the AET approach for evaluating the potential effects of sediment contamination. For reasons discussed earlier in this section, derivation of sediment quality values for the Section 403 program using the AET approach may or may not be appropriate, but all of these Puget Sound programs demonstrate the desirability of incorporating sediment quality values into the decision-making framework for Section 403. Similarly, the common use of biological indicators in these decision-making frameworks provides a valuable model for the development of technical guidance for the Section 403 program, whether or not the same indicators are selected for use nationwide. The decision-making frameworks of the Puget Sound regulatory programs also demonstrate how modeling techniques can be used as analytical tools in the evaluation of environmental impacts. Whereas generalized model runs, using a minimum of site-specific data, may be valuable in screening-level analyses conducted as part of determinations of no irreparable harm (see Section 7.2.1), more detailed model runs, using additional site-specific data to better characterize conditions in the receiving environment, can be valuable tools in determinations of no unreasonable degradation. Potential applications for Section 403 evaluations include modeling the relationship between contaminant source loading and accumulation of contaminants in the sediments (see Section 4.1.1), modeling sediment recovery processes (see Section 4.1.2), or evaluating the potential transport of discharged wastes into potentially sensitive areas, as required by the ocean discharge criteria (Table 1). The combined use of CORMIX and WASP4 in such applications represents significant improvements, with the capability of including far more pertinent processes, over the models previously used by EPA for modeling ocean discharges (see Section 4.1.1). Certain parallels have already been noted (Section 7.2.1) between the minor adverse effects allowed by several of the Puget Sound regulatory programs and effects that may be allowed under determinations of no irreparable harm. The ways in which the Puget Sound programs allow for minor adverse effects should also be considered for possible application in the technical guidance to be developed by EPA for determinations of no unreasonable degradation. It should be noted, for instance, that PSDDA allows for minor adverse effects on an ongoing basis at unconfined, open-water disposal sites (see Section 6.2), and that the Washington State Sediment Management Standards allow for minor adverse effects, at least on a temporary basis, within authorized sediment impact zones in the vicinity of permitted wastewater discharges (see Section 6.4). In both cases, consideration of the cost and technical feasibility of achieving compliance with a requirement for a lesser degree of impacts (e.g., requiring no discernible difference from background conditions) led to the conclusion that some minor adverse effects should be allowed. 97 ------- However, by only allowing minor adverse effects through the formal process of permitting dredged material disposal or permitting a wastewater discharge, the spatial extent of such effects can be managed, and there can be assurance that all necessary controls will be implemented to minimize such adverse effects. Both the Commencement Bay Superfund investigations (see Section 6.1) and the Washington State Sediment Management Standards (see Section 6.4) also allow for some present adverse effects to be rectified through natural recovery processes. Section 7.2.1 described the use of preliminary ecological risk assessment models as screening tools in determinations of no irreparable harm. More detailed ecological risk assessment models (Section 4.3) are directly applicable to the types of evaluations likely to be conducted in support of determinations of no unreasonable degradation. These more detailed models have the capability of producing quantitative estimates of the probability and magnitude of ecological effects. Section 7.2.1 also described the use of simple human health risk assessment techniques as screening tools in determinations of no irreparable harm. More advanced applications of these techniques might be considered for use in Section 403 determinations of no unreasonable degradation. Similar applications in the Puget Sound programs have included attempts to minimize human health risks associated with the consumption of contaminated seafood through: ¦ The development of a method for deriving site-specific surface water cleanup standards (see Section 3.2.4) ¦ The development of a sediment quality criterion for PCBs in Commencement Bay (see Section 4.2.1) ¦ The use of bioassays with contaminated sediments for assessing the potential for excessive bioaccumulation in marine organisms (see Section 4.2.2). Finally, analogies between monitoring to be required under determinations of no irreparable harm and monitoring now being required of major Puget Sound dischargers have already been discussed (Section 7.2.1). Monitoring of the receiving environment to support determinations of no unreasonable degradation will likely rely on many of the same types of sediment and water quality assessment tools now being used in Puget Sound (see Section 3). 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