managing wastewater in coastal urban areascentlib.ajums.ac.ir/multimediafile/58587647-4-1.pdf ·...

Managing WastewaterIn Coastal Urban Areas

Committee on Wastewater Management for Coastal Urban AreasWater Science and Technology Board

Commission on Engineering and Technical SystemsNational Research Council

NATIONAL ACADEMY PRESSWashington, D.C. 1993

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Copyright © National Academy of Sciences. All rights reserved.

Managing Wastewater in Coastal Urban Areas http://www.nap.edu/catalog/2049.html

http://www.nap.edu/catalog/2049.html

NATIONAL ACADEMY PRESS 2101 Constitution Ave., N.W. Washington, DC 20418

NOTICE: The project that is the subject of this report was approved by the Governing Board of theNational Research Council, whose members are drawn from the councils of the National Academyof Sciences, the National Academy of Engineering, and the Institute of Medicine. The members ofthe committee responsible for the report were chosen for their special competencies and with regardfor appropriate balance.

This report has been reviewed by a group other than the authors according to proceduresapproved by a Report Review Committee consisting of members of the National Academy of Sci-ences, the National Academy of Engineering, and the Institute of Medicine.

Support for this project was provided by the National Academy of Engineering, National Sci-ence Foundation Grant No. BCS-9002867, U.S. Environmental Protection Agency Contract No.X-817001-01-0, the City of San Diego, the Freeman Fund of the Boston Society of Civil Engineers,and National Oceanic and Atmospheric Administration Contract No. 50-DGNC-900139.Library of Congress Cataloging-in-Publication Data

Managing wastewater in coastal urban areas / Committee on Wastewater Management forCoastal Urban Areas, Water Science and Technology Board, Commission on Engineering and Tech-nical Systems, National Research Council.

p. cm.

ISBN 0-309-04826-5

1. Sewage disposal. 2. Runoff—Environmental aspects. 3. Coastal zone management. I.National Research Council (U.S.). Committee on Wastewater Management for CoastalUrban Areas.

TD653.M34 1993628.1'682—dc20 93-1845CIP

Copyright 1993 by the National Academy of Sciences. All rights reserved.

Printed in the United States of America

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COMMITTEE ON WASTEWATER MANAGEMENT FORCOASTAL URBAN AREAS

JOHN J. BOLAND, Chair, Johns Hopkins University, Baltimore, MarylandBLAKE P. ANDERSON, County Sanitation Districts of Orange County,

Fountain Valley, CaliforniaNORMAN H. BROOKS, California Institute of Technology, PasadenaWILLIAM M. EICHBAUM, The World Wildlife Fund, Washington, D.C.LYNN R. GOLDMAN, California Department of Health Services, EmeryvilleDONALD R. F. HARLEMAN, Massachusetts Institute of Technology,

CambridgeROBERT W. HOWARTH, Cornell University, Ithaca, New YorkROBERT J. HUGGETT, Virginia Institute of Marine Sciences, Gloucester PointTHOMAS M. KEINATH, Clemson University, Clemson, South CarolinaALAN J. MEARNS, National Oceanic and Atmospheric Administration,

Seattle, WashingtonCHARLES R. O'MELIA, Johns Hopkins University, Baltimore, MarylandLARRY A. ROESNER, Camp Dresser & McKee Inc., Orlando, FloridaJOAN B. ROSE, University of South Florida, TampaJERRY R. SCHUBEL, State University of New York at Stony Brook

WSTB LIAISON

RICHARD A. CONWAY, Union Carbide Corporation, South Charleston, WestVirginia

PANEL ON ENVIRONMENTAL PROCESSES

NORMAN H. BROOKS, Chair, California Institute of Technology, PasadenaWAYNE R. GEYER, Woods Hole Oceanographic Institution, Woods Hole,

MassachusettsROBERT J. HUGGETT, Virginia Institute of Marine Sciences, Gloucester PointGEORGE A. JACKSON, Texas A & M University, College StationALAN J. MEARNS, National Oceanic and Atmospheric Administration,

Seattle, WashingtonCHARLES R. O'MELIA, Johns Hopkins University, Baltimore, MarylandDONALD W. PRITCHARD, Professor Emeritus, The University at Stony

Brook, New York (resigned 9/6/91)JERRY R. SCHUBEL, State University of New York at Stony Brook

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PANEL ON HEALTH, ECOSYSTEMS, AND AESTHETICS

LYNN R. GOLDMAN, Chair, California Department of Health Services,Emeryville

WILLIAM M. EICHBAUM, The World Wildlife Fund, Washington, D.C.ROBERT W. HOWARTH, Cornell University, Ithaca, New YorkROBERT J. HUGGETT, Virginia Institute of Marine Sciences, Gloucester PointALAN J. MEARNS, National Oceanic and Atmospheric Administration,

Seattle, WashingtonJOAN B. ROSE, University of South Florida, Tampa

PANEL ON POLICIES, INSTITUTIONS, AND ECONOMICS

JOHN J. BOLAND, Chair, Johns Hopkins University, Baltimore, MarylandJOHN M. DeGROVE, Florida Atlantic University/Florida International

University, Fort LauderdaleWILLIAM M. EICHBAUM, The World Wildlife Fund, Washington, D.C.KATHERINE FLETCHER, Campaign for Puget Sound, Seattle, Washington

PANEL ON SOURCE CONTROL AND PUBLICLY OWNEDTREATMENT WORKS TECHNOLOGY

THOMAS M. KEINATH, Chair, Clemson University, Clemson, South CarolinaBLAKE P. ANDERSON, County Sanitation Districts of Orange County,

Fountain Valley, CaliforniaTAKASHI ASANO, University of California, DavisGLEN T. DAIGGER, CH2M Hill, Denver, ColoradoDONALD R. F. HARLEMAN, Massachusetts Institute of Technology,

CambridgeBILLY H. KORNEGAY, Engineering-Science, Inc., Fairfax, VirginiaJAMES F. KREISSL, U.S. Environmental Protection Agency, Cincinnati, OhioJOSEPH T. LING, 3M Company (retired), St. Paul, MinnesotaP. AARNE VESILIND, Duke University, Durham, North Carolina

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PANEL ON SOURCES

LARRY A. ROESNER, Chair, Camp Dresser & McKee Inc., Orlando, FloridaJAMES P. HEANEY, University of Colorado, BoulderVLADIMIR NOVOTNY, Marquette University, Milwaukee, WisconsinWILLIAM C. PISANO, Havens and Emerson, Inc., Boston, MassachusettsStaffSARAH CONNICK, Study DirectorPATRICIA L. CICERO, Senior Project AssistantJACQUELINE MACDONALD, Staff OfficerLYNN KASPER, Editorial AssistantInternsBETH C. LAMBERT, Summer InternSUSAN MURCOTT, Marblehead, Massachusetts

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WATER SCIENCE AND TECHNOLOGY BOARD

DANIEL A. OKUN, Chair, University of North Carolina, Chapel HillA. DAN TARLOCK, Vice Chair, Illinois Institute of Technology, Chicago-

Kent College of LawJ. DAN ALLEN, Chevron USA, Inc., New Orleans, LouisianaKENNETH D. FREDERICK, Resources for the Future, Washington, D.C.DAVID L. FREYBERG, Stanford University, Stanford, CaliforniaWILFORD R. GARDNER, University of California, BerkeleyDUANE L. GEORGESON, Metropolitan Water District of Southern California,

Los AngelesLYNN R. GOLDMAN, California Department of Health Services, EmeryvilleWILLIAM GRAF, Arizona State University, TempeTHOMAS M. HELLMAN, Bristol-Myers Squibb Company, New York, New

YorkROBERT J. HUGGETT, Virginia Institute of Marine Science, Gloucester PointCHARLES C. JOHNSON, Consultant, Bethesda, MarylandJUDY L. MEYER, University of Georgia, AthensSTAVROS S. PAPADOPULOS, S. S. Papadopulos & Associates, Inc.,

Rockville, MarylandKENNETH W. POTTER, University of Wisconsin, MadisonBRUCE E. RITTMANN, Northwestern University, Evanston, IllinoisPHILIP C. SINGER, University of North Carolina, Chapel HillJOY B. ZEDLER, San Diego State University, San Diego

Staff

STEPHEN D. PARKER, DirectorSARAH CONNICK, Senior Staff OfficerSHEILA D. DAVID, Senior Staff OfficerCHRIS ELFRING, Senior Staff OfficerGARY KRAUSS, Staff OfficerJACQUELINE MACDONALD, Staff OfficerJEANNE AQUILINO, Administrative AssociateANITA A. HALL, Administrative AssistantPATRICIA L. CICERO, Senior Project AssistantGREGORY K. NYCE, Senior Project Assistant

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The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Bruce M. Alberts is president of the National Academy of Sciences.

The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Robert M. White is president of the National Academy of Engineering.

The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Kenneth I. Shine is president of the Institute of Medicine.

The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy’s purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Bruce M. Alberts and Dr. Robert M. White are chairman and vice chairman, respectively, of the National Research Council.

www.national-academies.org

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Preface

At least 37 percent of the U.S. population is located in counties adjacent tothe oceans or to major estuaries, most of them in relatively concentrated urbanareas. The waste from this population and its associated activities is a majorcontributor to the widely documented deterioration of ocean and coastal waters.Beaches are closed, fisheries and shellfish beds are quarantined, and, in manyareas, harbor sediment has become so contaminated that dredging cannot beaccomplished safely. The U.S. Environmental Protection Agency (EPA) andothers have expressed concern over the relative lack of progress in improvingthe quality of estuarine and coastal waters. However, two of the most highlypublicized coastal wastewater policy disputes in the late 1980s involved casesof alleged overcontrol. Both Boston and San Diego complained that they werebeing asked to provide upgraded wastewater treatment facilities that wouldproduce no significant improvement in ocean water quality at great costs.

A number of factors combined to focus the attention of the Water Scienceand Technology Board (WSTB) on this issue. First was the conspicuousparadox of complaints of overcontrol in the midst of widespread concern overdeteriorating water quality. Another notable feature was the large amount ofmoney involved: both Boston and San Diego face secondary treatmentconstruction costs on the order of several billion dollars. Finally, there had beenno outside review of the policies laid down by the Clean Water Act since theNational Commission on Water Quality report in 1975. Consequently, in 1989,at the direction of Congress, the EPA requested that the WSTB advise theagency on opportunities to improve wastewater management policy for coastalurban areas in the future.

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The WSTB then initiated the study that led to this report. Financial supportwas provided by the EPA, the National Science Foundation, the NationalOceanic and Atmospheric Administration, the City of San Diego, the FreemanFund of the Boston Society of Civil Engineers, and the National Academy ofEngineering. The Committee on Wastewater Management for Coastal UrbanAreas was formed and charged with the completion of various aspects of thisstudy. The Statement of Task required the Committee to examine issuesrelevant to wastewater management in urban coastal areas. Among other things,the Committee was directed to consider:

• environmental objectives, policies, and regulations;• technology and management techniques; and• systems analysis and design, including environmental modeling.

The Committee was not asked to review past decisions. Instead, it wasdirected to identify opportunities for improving the current system throughwhich coastal urban wastewater and stormwater are managed.

The Committee consisted of fifteen engineers, scientists, andenvironmental policy specialists. The first meeting was held in Washington,D.C. in May 1990. As a result of its initial assessment of the problem, theCommittee formed five panels with a combined membership of 30, includingthe Committee members. The Committee met six times and heard from a widerange of local, state, and federal officials, as well as independent engineers andscientists and other concerned individuals. The panels met more than 20 times,and additional meetings were held by an executive subcommittee and aneditorial subcommittee.

It is fair to say that the Committee experienced more than the usual amountof difficulty in preparing this report. The problems arose, not from anysignificant disagreement among the members, but from uncertainty about howto present the Committee's findings. On the one hand, the Committee hasassembled much information of immediate use to wastewater managementpractitioners, much of it never before published: comparisons of treatmentprocesses, design procedures, a guide to risk management, and evaluations ofalternative regulatory instruments. On the other hand, the report provides awide-ranging critique of existing wastewater management policy and proposesa new and fundamentally different paradigm: integrated coastal management.

The Committee's problem was to present the practical information withoutobscuring the policy recommendations and to highlight the policyrecommendations without crowding out the practical data. This reportrepresents a set of compromises reached after several major changes of outlineand countless revisions. It expresses the consensus of the Committee, but it failsto capture everything that every member would have wished.

The issues addressed by the Committee take place within complex and

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diverse institutional and political structures. Also, as may be expected, data onthe progress and status of water quality improvement efforts are less thancomplete in most cases, and because of site-specific and methodologicaldifferences difficult to compare from one case to another. As much of theavailable information on experiences with existing policies is less thancomplete, and therefore perhaps subject to broad interpretation, therecommendations in this report reflect the collective judgement of theCommittee and are based on a substantial examination of experiences aroundthe nation.

In reaching its conclusions, the Committee consulted with more than 150distinguished scientists, engineers, public officials, regulators, and citizens (seeAppendix G). The Committee is grateful to them for sharing their knowledge,insights, and accumulated experience in these matters. The quality andusefulness of this report has been improved immeasurably by this assistance, sogenerously offered. Any errors or shortcomings are, of course, the responsibilityof the Committee.

In the course of this study, a large volume of material was transmitted to,among, and from Committee and panel members. The reports and papersreviewed at various times in the life of the Committee now amount to more thanone meter of shelf space. Another meter would be needed for all of the meetingnotebooks, panel reports, and Committee report drafts. The management of thisflood of material, along with the arrangement of meetings and monitoring of thecomings and goings of Committee and panel members, adds up to a formidableworkload interspersed with numerous deadlines. Despite the size of this task,everything was done as needed calmly and efficiently by Senior ProjectAssistant Patricia Cicero and her colleagues in the office of the Water Scienceand Technology Board.

Several other WSTB staff members must be mentioned here. WSTBDirector Stephen D. Parker was one of the first to understand the need for thisstudy. He guided and shaped the concept through nearly two years ofpreliminary discussions and was instrumental in securing adequate financialsupport. He continued to provide advice and perspective throughout the life ofthe study. Additional assistance was provided by Research Associate JacquelineMacDonald, who served as staff to one of the panels.

Special thanks are due, as well, to Susan Murcott, a graduate student at theMassachusetts Institute of Technology, who began working with the Committeeas a 1990 Summer Intern. Following that summer, Susan continued herassociation with the Panel on Source Control. She served as a researcher andtechnical writer, making many important contributions to the panel's report.

To the extent that this report serves its intended purpose, the major creditbelongs to Study Director Sarah Connick. Sarah had the overall responsibilityfor managing the numerous activities that made up the study

PREFACE xi

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and for insuring that the final product met the expectations of the Board and theCommittee. It would be accurate to say that she carried out this responsibilityfully and with complete professionalism, but that would miss the point. Sarahwas, in a very real sense, a contributor to this project as well as its staff director.Her knowledge, judgment, and sense of balance were always present, evenwhen the Chair and other Committee members temporarily lost their way.Whatever usefulness this report may have in the public policy arena is largelydue to Sarah's consistent attention to purpose and priorities.

Finally, we return to the subject of Boston, San Diego, and other situationswhere waivers from the Clean Water Act's secondary treatment requirementwere requested. Amid much controversy, San Diego's application waswithdrawn and Boston's was not approved. The provision of the Act underwhich waivers are administered, Section 301(h), continues; however, theopportunity to enter the program has since expired. Meanwhile these and otherrelevant controversies live on. This report will doubtless be scrutinized bypersons on all sides of these controversies, seeking evidence of the Committee'sviews.

The Committee makes no explicit recommendations on these or any otherspecific cases. Rather, the report offers a detailed proposal for the way in whichcoastal wastewater systems should be planned and such issues should beconsidered in the future. The approach the Committee advocates, integratedcoastal management, is more demanding in many ways than existingwastewater management policy, but it is inherently flexible in application. Thekey decisions in the Boston and San Diego cases were made within the morerigid context of existing policy. Whether these decisions were correct at thetime is an issue that the Committee did not address. Whether findings in thisreport will permit any of these decisions to be revisited is essentially a legalmatter that is outside the purview of a National Research Council committee.The Committee does believe the report contains technical information andanalysis that should be immediately useful to coastal areas faced withenvironmental problems. In addition, the wastewater management policyproposed here will greatly improve the ability to resolve future conflicts in thebest interests of the environment and the community.

JOHN J. BOLAND, Chair

Committee on Wastewater Management for Coastal Urban Areas

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Contents

EXECUTIVE SUMMARY 1 The Current Approach to Wastewater Management in Coastal

Areas 2

Key Issues Relating to Wastewater and Stormwater Manage-ment

7

Integrated Coastal Management 13 References 19

1 INTRODUCTION 20 Stresses on the Coastal Environment 21 Wastewater and Stormwater Management 23 The Current Approach to Wastewater and Coastal Management 31 Progress in Managing Water Quality 32 Challenges for the Future 41 References 51 CASE HISTORIES Boston 42 San Diego 47

BOX The Coastal Zone 35

2 KEY ISSUES RELATING TO WASTEWATER ANDSTORMWATER MANAGEMENT

53

Regional Differences 53 Nutrients in Coastal Waters 54 Source Control and Water Conservation 55 Levels of Treatment 56 Stormwater and Combined Sewer Overflows 61 Detecting Human Pathogens 65

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Developing Management Alternatives 68 Evaluation and Feedback 69 Summary 70 References 71

3 INTEGRATED COASTAL MANAGEMENT 74 Developing a Sustainable Vision 74 Principles and Methodology for a System of Integrated

Coastal Management 76

Conclusion 85 References 86

4 THE PROCESS 88 Dynamic Planning 88 Selection, Policy, and Institutions 144 Monitoring, Information Management, and Research 149 Summary 151 References 152 CASE EXAMPLE Santa Monica Bay 114 BOXES Setting Goals and Defining Domains for Nutrient Control in

the Chesapeake Bay 96

The California Ocean Plan 127

5 BENEFITS, BARRIERS, SOLUTIONS, AND IMPLEMENTA-TION

155

Introduction 155 Benefits 158 Barriers and Solutions 160 Implementation 165 Wastewater Management for the Next Century 172 Reference 173

APPENDIXES A THE ROLE OF NUTRIENTS IN COASTAL WATERS 177

Adverse Consequences of Eutrophication and NuisanceAlgae

178

Controls on Eutrophication and Nuisance Blooms inCoastal Waters

182

Conclusions 194 Reference 195

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B MICROBIAL PATHOGENS IN COASTAL WATERS 203 Microbiologic Agents Associated with Wastewater 203 Occurrence of Pathogens in Coastal Waters 210 Survival of Enteric Microorganisms in Marine Waters 214 Illnesses from Bathing 217 Risk Assessment Approach for Microorganisms 218 Summary of Shellfish and Recreational Microbiologic Risks 224 References 226

C TRANSPORT AND FATE OF POLLUTANTS IN THECOASTAL MARINE ENVIRONMENT

231

Introduction 231 Mechanisms of Input 233 Transport and Fate 240 Overall Design of Disposal Systems, Control of Diffuse

Sources, and Use of Models 276

Summary 287 References 288

D ENGINEERING AND MANAGEMENT OPTIONS FORCONTROLLING COASTAL ENVIRONMENTALWATER QUALITY

295

Introduction 295 Source Control 295 Municipal Wastewater Treatment 309 Disinfection 344 Combined Sewer Overflow Controls 350 Nonpoint Source Management Options 366 References 387

E POLICY OPTIONS AND TOOLS FOR CONTROLLINGCOASTAL ENVIRONMENTAL WATER QUALITY

394

The Institutional Setting 394 Management Tools 398 Financing Mechanisms 424 References 430

F BIOGRAPHICAL SKETCHES 431G CONTRIBUTORS TO THE COMMITTEE'S EFFORT 443

INDEX 451

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Managing Wastewater

In Coastal Urban Areas

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Executive Summary

Although significant progress has been made in improving the nation'swater quality over the past 20 years, many coastal areas continue to suffer frompersistent environmental problems and can expect to encounter new problems inthe future. Today's coastal water-quality management practices do not provideadequate protection from some types of problems and in some cases areoverprotective of other types of problems. Much of the debate over how toprotect and improve coastal water-quality has focused on urban wastewater andstormwater management.

This report, as requested of the National Research Council by the U.S.Environmental Protection Agency (EPA) at the direction of Congress, examinesissues relevant to wastewater management in coastal urban areas. These issuesinclude environmental objectives, policies, and regulations; technology;management techniques; systems analysis and design; and environmentalmodeling. The National Research Council was not asked to review past policiesor decisions. Instead, it was directed to identify opportunities for improving thecurrent system through which coastal urban wastewater and stormwater aremanaged. The report identifies several key areas in which specific progresscould be made, and recommends a new framework for coastal managementtoward which current management practices should evolve. It addresses themanagement of marine and estuarine areas in particular and does not considerthe Great Lakes.

The scope of activities involved in the management of wastewater andstormwater in coastal cities is large and complex. In the broadest terms, thepurpose of managing these wastes is to protect the environment while using

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it for waste disposal. At least 37 percent of the United States' population residesalong the coast, mostly in urban areas. More than 1,400 municipal wastewatertreatment plants provide service to the coastal population, discharging 10 billiongallons of treated effluent per day. During the period from 1972 to 1992, about$76 billion were spent in constructing or expanding publicly owned treatmentworks; $50 billion of this total came from federal grants. At an estimatedoperating cost ranging from $300 to $500 per million gallons of treated effluent,the national expenditure for operating these plants is between $1.1 billion and$1.8 billion per year.

The management of wastewater and stormwater in coastal urban areastakes place in the context of a multitude of other human activities and naturalprocesses within the coastal zone. Some major factors that cause perturbationsin the coastal zone include, in no special order, municipal wastewater andstormwater discharges; combined sewer overflows; other urban runoff; directindustrial wastewater discharges; agricultural runoff; atmospheric deposition;ground water flow; boating traffic; shipping; dredging and filling; leaching ofcontaminated sediments; oil and gas production; introduction of nonindigenousspecies; harvesting of fish and shellfish; freshwater impoundment anddiversion; and land-use changes in coastal drainage basins.

THE CURRENT APPROACH TO WASTEWATERMANAGEMENT IN COASTAL AREAS

While treatment plant and outfall technologies often dominate discussionsof wastewater issues, they are only two of many important pieces that togethermake up a coastal wastewater management strategy. Other, less visiblecomponents of a management strategy include source control efforts todiscourage the production of undesirable wastes and prevent their introductioninto wastewater and stormwater drainage systems; education to encouragechanges in behavior such as appropriate methods for disposal of automobile oil;monitoring to assure compliance and ascertain the effectiveness of managementstrategies; and environmental studies to improve understanding of the impact ofwastewater management strategies and point toward opportunities forimprovement. Water conservation and reclamation programs also can beimportant components of an integrated strategy.

Federal Legislation

Current wastewater and stormwater management policies are rooted in the1972 amendments to the Federal Water Pollution Control Act, reauthorized in1977 and 1987 as the Clean Water Act. The 1972 act set the nation on afundamentally new course for protecting its waters. It asserted federal

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authority over the quality of navigable waters, required the establishment ofuniform minimum federal standards for municipal and industrial wastewatertreatment, set strict deadlines for compliance, established a national dischargepermit system, and provided substantial amounts of federal grant money to helppay for the newly required projects. The 1972 act resulted in a tremendouseffort to control water pollution and produced notable water-qualityimprovements around the country, particularly in rivers and lakes.

While the approach laid out in the 1972 act produced rapid and effectiveimprovements in many areas, it has not always allowed a process thatadequately addresses regional variations in environmental systems around thecountry or responds well to changing needs, improved science, and morecomplete information. A provision in the 1977 Clean Water Act attempted torecognize the differences in how municipal wastewater discharges affect marinewaters versus freshwater rivers, lakes, and streams. For a limited time, coastalpublicly owned treatment works (POTWs) were allowed to apply for waiverswhich would exempt them from the federal minimum requirement of secondarytreatment if they were able to demonstrate that their treatment and disposalpractices provided adequate protection of the environment.1 Dischargers whowere granted waivers also had to institute source control and monitoringprograms that went far beyond those required for dischargers that met thetechnology-based requirement.2 The opportunity to apply for an initial waiverexpired at the end of 1982; some applications are still pending. Approximately40 dischargers are currently operating under waivers; they range from smallcommunity systems in the continental United States, Alaska, Hawaii, and thetrust territories, to large municipal systems such as the County SanitationDistricts of Orange County, California.

Progress and Emerging Concerns

As improvements have been made in the quality of point sourcedischarges, the impacts of other sources of pollution, diffuse or nonpointsources, have become more apparent. In some areas, even if pollution from allpoint sources were controlled, nonpoint contributions would still causesignificant environmental problems. Thus, any solution to coastal environmental

1 Section 301(h) of the Clean Water Act requires that applicants demonstrate ''theattainment or maintenance of water quality which assures . . . protection and propagationof a balanced, indigenous population of shellfish, fish and wildlife, and allows recreationactivities, in and on the water", in addition to source control, monitoring, and otherrequirements.

2 Technology-based requirements are performance standards based on the capability ofan existing technology, as opposed to performance standards based on the receivingwater requirements.

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problems must address the entire range of sources of disruption that causesadverse impacts.

Since 1972, important changes have taken place in government, science,engineering, and the expectations of the public in regard to wastewater andstormwater management and environmental protection. Budget limitations at alllevels of government point to the need to spend public money more efficiently.Much has been learned from experience in managing coastal environments.Advances in science have greatly improved understanding of coastalenvironmental processes, and advances in engineering have led to thedevelopment and use of improved technologies for managing coastal resources.As a result of the 1972 act, there is now a well developed permitting system forpoint source dischargers coupled with a federal enforcement authority.

Constituents of Concern

Wastewater and stormwater management strategies focus on controllingthe release of potentially harmful constituents to the environment. As with anyactivity that affects the environment, the potential for harm depends on themagnitude of the insult, where it occurs, and the characteristics of the stress. Ingeneral, a wastewater constituent may be considered to be of high concern if itposes significant risk to human health or ecosystems well beyond points ofdischarge and is not under demonstrable control. A wastewater constituent maybe generally considered to be of lower concern if it causes only local impact oris under demonstrable control.

In the collective judgement of the Committee, in general, it may beanticipated that national level priorities for wastewater constituents in coastalurban areas over the next several decades will be as described below andsummarized in Table ES.1. It is noted, however, that priorities may differ at thelocal and regional level depending on site-specific circumstances.

High Priority

Nutrients. Many estuaries of the Atlantic and Gulf coasts currentlyexperience widespread eutrophication from excess inputs of nutrients, usuallynitrogen, and more are vulnerable to excess nutrient enrichment. Secondarytreatment does not remove significant amounts of nitrogen from wastewater.Nutrients come from a variety of point and diffuse sources. To adequatelyaddress their effects on coastal water bodies, all relevant sources need to beidentified and compared, and the most important inputs reduced or otherwisediverted.

Pathogens. Over 100 pathogenic viruses and bacteria have been identifiedin runoff and sewage. Numerous shellfish beds and bathing beaches

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are closed due to unacceptable levels of coliform bacteria each year. However,neither the true extent of contamination by actual human pathogens nor thedominant sources of contamination are adequately known in most regions.

TABLE ES.1 Anticipated National-Level Priorities for Constituents of Concern

Priority Pollutant Groups ExamplesHigh Nutrients Nitrogen

Pathogens Enteric virusesToxic organic chemicals PAHs

Intermediate Selected trace metals LeadOther hazardous materials Oil, chlorinePlastics and floatables Beach trash, oil, and grease

Low Biochemical oxygen demand (BOD)Solids

NOTE: Within each priority group the order of listing does not indicate further ranking.

Toxic Organic Chemicals. Chronic industrial and wastewater point sourcesof toxic chemicals such as chlorinated dioxins, polynuclear aromatichydrocarbons (PAHs), and solvents have been identified and controlled or arereadily subject to control with existing technology. In fish and shellfish, levelsof some toxic organics (including chemicals no longer produced in the UnitedStates, such as PCBs and DDT) are dropping nationwide, while others such aspetroleum hydrocarbons are apparently not declining. Urban runoff, combinedsewer overflows and contaminated sediments due to past uncontrolleddischarges are major continuing sources of toxic organic chemicals in manycoastal urban areas. Although the original source of contamination may havebeen controlled, contaminated sediments may continue to be secondary sourcesof contamination to fish, shellfish, and seabirds for many years or decades.

Intermediate Priority

Metals. Elevated concentrations of potentially toxic metals such asmercury, cadmium, and tin are still found in shellfish in localized urban areas,but these problems are not large-scale or region-wide concerns. Dissolvedmetals may affect species distributions in coastal ecosystems. Most metals donot biomagnify through marine food webs. Source control has been effective inseveral areas in reducing concentrations. Future problems

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can be expected to be with lead and localized cases of contamination byorganometals. As with toxic organic chemicals, metals from past uncontrolleddischarges still contaminate sediments especially near harbors, and can be asignificant source of contamination to overlying waters and local aquatic life.

Oil and Other Hazardous Materials. The probability of major oil spills islow, but their immediate impacts on coastal ecosystems and local industries(e.g., fishing, tourism) can be devastating. Of greater consequence, however,are the thousands of unpublicized small spills and leaks (e.g., illegal disposal ofused automobile crankcase oil in storm drains) which occur daily in coastalurban areas and may add up to large chronic inputs of petroleum hydrocarbons.

Toxic chemicals used in wastewater treatment (e.g., chlorine compounds)and industrial and commercial settings (e.g., solvents, arsenicals) aretransported across urban coastal areas and subject to accidental release. Thoughnot a central part of the wastewater management issue, spills need to beaccounted for in addressing coastal quality issues.

Floatables and Plastics. Beaches continue to be fouled by trash from land-based sources, especially following episodic weather conditions such as stormsand unusual changes in coastal currents. Marine debris poses hazards to wildlifeas well as people, and is aesthetically displeasing. There is considerableopportunity for use of predictive simulation models, such as oil spill trajectorymodels, to identify sources of marine debris and develop control strategies.

Low Priority

Biochemical Oxygen Demand (BOD). In open coastal waters and well-flushed estuaries, oxygen depletion due to BOD from wastewater dischargedthrough a well-designed outfall is generally not of ecological concern. In thesesituations, organic material from wastewater is a minor, localized cause ofoxygen depletion, especially relative to that due to nutrients. In most coastalurban areas in which BOD from wastewater is of significant concern, it is beingcontrolled under existing requirements.

Solids. Settleable and suspended solids from large wastewater outfallswere once the major cause of localized accumulations of anaerobic sedimentsand damaged seafloor ecosystems. Where they were significant in the UnitedStates (e.g., large municipal outfalls, pulp mills), these conditions have beencontrolled with primary or advanced treatment, and high dilution outfalls.Today, the degree of solids removal required is driven by the need to protectsediments from accumulations of particle-associated

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pollutants. Heavy urban runoff, including combined sewer overflows (CSOs), insome areas may still be a source of localized solids accumulations and warrantcontrol.

KEY ISSUES RELATING TO WASTEWATER ANDSTORMWATER MANAGEMENT

The Committee identified seven specific areas which present opportunitiesfor improving wastewater management in coastal urban areas. Then, based onits analysis of these and other issues, the Committee proposes a new frameworkfor managing coastal waters, integrated coastal management.

Regional Differences

Finding: Because of the wide variations encountered in coastal systems, itis not possible to prescribe a particular technology or approach at the nationallevel that will address all water quality issues at all locations satisfactorily. Anysuch approach would necessarily fail to protect resources in some coastalregions and would place excessive and unnecessary requirements on others.

Recommendation: Coastal wastewater and stormwater managementstrategies should be tailored to the characteristics, values, and uses of the particular receiving environment based on a determination of what combination of control measures can effectively achieve water and sedimentquality objectives.

Discussion: The environmental effects of a POTW discharge from anoutfall or urban stormwater from a shoreline outlet depend strongly on thephysical, chemical, and biological nature of the receiving water body, and itsgeography and bathymetry. The degree of flushing of the receiving water withrelatively uncontaminated ocean water is a major factor in determining theconcentration of nutrients or persistent contaminants in coastal or estuarinewaters. In general, this coastal exchange is much slower for the estuaries andshallow coastal shelf waters along the East and Gulf coasts than for the deepernarrow shelf waters of the Pacific coast.

The opportunity for accumulation of wastewater particles and anyassociated pollutants in bottom sediments also depends greatly on receivingwater characteristics. Estuaries may trap sediments and pollutants becauseflocculation is enhanced where fresh water mixes with salt water. Along theopen coasts, deposition is more likely to occur in areas with slow currents andlimited exchange with deep water.

Finally the resources to be protected, and water and sediment qualityobjectives may be quite different among various regions and discharge sites.

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The engineering and scientific capability needed to account for thesevariations has developed significantly over the past 20 years.

Nutrients in Coastal Waters

Finding: Nutrient enrichment, primarily due to nitrogen, is an importantproblem in many estuarine and some coastal marine systems.

Recommendation: Greater attention should be focused on preventing excess regional enrichment of nitrogen and other nutrients at levels that areharmful to ecosystems.

Discussion: Nutrient enrichment can cause oxygen depletion, reduced fishand shellfish populations, nuisance algal blooms, and dieback of seagrasses andcorals. While not known to be a problem along much of the open Pacific coast,excess nutrient enrichment, or eutrophication, is a persistent problem in manyestuaries, bays, and semi-enclosed waterbodies along the Atlantic and Gulfcoasts, and may even be of concern over a large scale in some more open areasalong these coasts. Nitrogen controls primary production and eutrophication inmost temperate estuaries and coastal waters, although phosphorus can be ofconcern in many tropical waters and perhaps in some temperate estuaries. Bycontrast, in freshwater systems, phosphorus is almost always the nutrientlimiting growth. It may be important to keep nitrogen and phosphorusconcentrations low relative to silicon to avoid causing nuisance algal bloomssuch as red and brown tides.

Both the sources of nutrients to coastal waters and the associated effectsoccur at the regional scale making them difficult to measure, assess, andmanage. Nutrient inputs to coastal waters come from both point and diffusesources including wastewater treatment plants, agricultural runoff, urban runoff,ground water seepage, atmospheric deposition, and release of previouslyaccumulated nutrients from bottom sediments.

Source Control and Water Conservation

Findings: 1. Reduction or elimination of pollutants at their sources is aneffective tool for managing both point and diffuse sources. Forexample, for trace metals and toxic organics, source control ismore efficient than removal at central plants, which may thenhave problems of safe disposal of large volumes of contaminatedsludge.

2. Water conservation reduces the volume of sewage requiringcollection and treatment, however, it does not change the totalmass of wastewater pollutants; in fact, pollutant concentrationsmay actually be increased. The benefits of water conser

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vation include reduced cost of facilities for water supply and wastewater treatment,and reduced impacts in the region from which surface or ground water supplies areextracted.

Recommendation: Source control of pollutants should be stronglyencouraged by incentives and regulation.

Discussion: Many toxic substances are difficult and/or expensive toremove from wastewater. Often, however, these materials can be preventedfrom entering the wastestream or significantly reduced in amount throughpollution prevention programs. For example, industrial pretreatment and sourcecontrol programs have already achieved significant reductions of trace metals,toxic organics, and oil and grease in the influent and thus in the effluent andsludge products from municipal wastewater treatment plants (AMSA 1990). Inthe case of urban runoff, erosion controls at construction sites, street sweeping,storm drain warning signs, and public education efforts have led toimprovements in some areas. In new developments, stormwater designs cansignificantly slow runoff and increase infiltration into the ground and improvestormwater quality.

Levels of Treatment

Findings: 1. Important water and sediment quality problems in the coastalzone include excessive levels of nutrients, pathogens, and toxicsubstances.

2. Toxic pollutants are often associated with particles in wastewaterdischarges. Particle removal is therefore a very importanttreatment step for protecting sediments from excessive carbonenrichment and accumulation of toxic substances.

3. Chemically-enhanced primary treatment has been usedsuccessfully to increase the removal of suspended solids inPOTWs. Removals of 80 to 85 percent have been achieved withlow doses of chemicals; higher removals are possible with higherdoses. This level of removal for suspended solids is nearlyequivalent to the EPA performance standard for secondarytreatment. EPA requires that 30-day averages for removal ofsuspended solids be at least 85 percent, with effluentconcentrations of less than 30 mg/l.

4. The depletion of dissolved oxygen (DO) is generally not ofecological concern in the ocean or in open coastal waters. Wherelow DO levels are of concern, as in some estuaries, they are morelikely to result from eutrophication by nutrients rather than frompoint source inputs of BOD. In these situations, secondary or anyother treatment implemented

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solely for BOD removal produces little improvement in receiving water quality.5. Implementation of an environmental quality-based approach in coastal areas

would require levels of treatment in POTWs that, depending on regional needsand receiving-water characteristics, will often be different, either higher orlower, than current requirements.

Recommendation: Coastal municipal wastewater treatment requirements should be established through an integrated process on the basis ofenvironmental quality as described, for example, by water and sediment qualitycriteria and standards, rather than by technology-based regulations.

Discussion: A wide array of wastewater treatment processes is available,however, the costs of treatment and volumes of waste sludges produced tend toincrease with increasing removal capabilities. Generally, it is simplest toremove large solids, oil, and grease, then BOD, and then nutrients. Someremoval of fine solids, toxic metals and organic substances, and pathogens canbe expected with most treatment systems.

Environmental and human health concerns associated with wastewatercontaminants differ depending on the location and mechanism of theirintroduction into coastal waters. Accordingly, wastewater treatment, sludgedisposal practices, and other management controls should be guided by waterand sediment quality requirements of the receiving waters. Wastewater solidsare of concern in most environments because of the possible toxicity ofassociated heavy metals, organic substances, and pathogens. BOD is of interestin most bays, estuaries, and semi-enclosed waterbodies because of the effects ofoxygen depletion on aquatic life. Widespread problems of oxygen depletion inestuaries and coastal waters are much more likely to result from excess nutrientenrichment than from BOD originating directly from wastewater flows. BODfrom wastewater flows is generally not important in the open ocean.

Chemically enhanced primary treatment is an effective technology forremoving suspended solids and associated contaminants. It has potentialapplication in situations where BOD is not a significant concern. It can also becombined with biological treatment for BOD and/or nutrient removal.

Stormwater and Combined Sewer Overflows

Finding: Urban runoff and CSOs are major contributors to water qualityproblems in coastal urban areas.

Recommendation: Stormwater and CSO abatement requirements should be based to the greatest extent possible on an understanding of regional

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